The Chicken & the EGG (conundrum)  ?                       
Top question why is my internet dead?         
As this pertains to your chip software  DRIVERS and for sure ETHERNET. (fast began in 1995, GIGA-lan 1998)

All the below assumes you tested your modem/router RJ45 jacks with another PC and it works there and connects to the internet , leaving only one problem,  the bad PC. (fixing it)
It is dead because the chip that does this is dead, not blown up but it's necessary software driver is missing (we call it a "driver") (if a driver is missing the PC OS can not talk to the chip at all) (missing corrupted or infected or wrong)
This is what makes Plug and Play fail (most times) PnP. (PnP is the MS "MicroSoft",  driver finding Engine -processes)
This PnP engine  looks for the driver first on your PCs windows folder that stores all drivers and in CAB files (ms compressed files) if not found then the PnP engine tries to get them from the Microsoft servers for driver.
XP and VISTA driver servers at MS are now shut down.  (and older) (but old updates are still there)
The chicken and egg deal is how to get a driver using that which is dead?. Ethernet (and wifi dead) If both are dead, you can't do this easy... (no connections to the internet now)  (the answer is simple use a connected PC)
The driver you get must match your OS version XP to W10 and must match 32bit or 64bit OS,  some drivers support both in one setup program... (read the facts pages first then download the driver)
The Device manager may show it missing or failing here is mine working ok(DM will show it missing,or in Red/yellow marks.)
The problem that perplexes many, is the chick&egg deal.  (the Lan CHIP is dead & wifi chip is dead)  (at this point most folks find wifi dead too, or its drivers missing too, and can't get wifi going now)
This means PnP is dead now, due to zero internet access, now. "no connections"

Photo #1: (the plug has  spring plastic lock, do not force it out, depress the TAB first)  T
he RJ45 Jack/plug  8pins and Cat5/6 cable.
Best in all cases is get the ETHERNET CHIP working first.  this is  Called wired Ethernet. It goes to your ROUTER.

Some PCs the onboard ethernet chip is not there but this PC has a Eternet card.  SEEN here.( the card needs a driver too , If you use it)
The best way to get PnP working is to go to a good PC.   (that has a working internet.) 

The steps are easy, but tedious. (10x more easy that Wifi)! and way faster to on any Gigalan router.
I will now do one of the most hard to do chip.
  1. Lets say the PC that is dead LAN, runs ok but the device manager shows the Ethernet chip is dead. clicking upgrade fails, due to no internet working, fixing this is like changing tires on a car,while driving. (impossible?. sure!)
  2. Lets say the chip is an old  nForce , lets say it's a 630i chip ,  is missing  its driver, due to say kids playing or Klingons attacking, or was Slammed?
  3. Lets say HP has no driver, now, over 10 years old, and say you have no idea what is under the large glue logic chip heatsink there on the mobo, well I do a PCI scan it, to find it.
  4. Go to any working PC, that has the internet working and get the chip driver off the wondrous  INTERNET.
  5. I go to Nvidia company.  (MS is no help nor is HP now) So we go direct (same with Nvidia Video cards)  We grabbing Nforce chip driver here. (one of the most hard to get but not impossible as many are)
  6. Lets say  you run the Virus Magnet XP, and find this page, type "legacy" in the first toggle box and get the EXE file from Nforce servers... there.
  7. You down load this and put it on your handy dandy USB memory stick (any size will work,  over say 500mB.)  XP is only 50mB sized.   (put in there directly or copy it there) your choice
  8. Then remove the USB stick from GOOD PC and put the same stick into the bad PC.
  9. Run the EXE on your stick and then let it run setup.exe inside it. this installed the full nforce drivers for this very complex chip.
  10. Reboot the bad PC now.  Bingo Ethernet shows up in the Device manager. (mine is Realtek)
  11. When working the LED's flash in the rear jack face of photo #1 and on  most routers too.
  12. The Task bar  Ethernet ICON will not have X marked across it, telling you the Ethernet is not dead.
  13. If still dead? X there,  use the control panel page on "Network and  sharing center", and click "trouble-shoot problems" or click "setup a new connection". (answer the questions there.)
If you can not get a good driver and is made by other makers, go to there website, download pages.  (run the PNP scan above first to learn what you have)  Top chip makers today  are...
In Google type intel download (you are there)
or Broadcom  download
or Atheros
or Intel   (eg: 82562GT)
or Renesas or Qualcomm, AMD, ON_SEMI and Marvell, and more...

Many chip makers are now gone, or stopped doing new drivers at XP.  or even stopped at Windows 2000. (vast makers of chips left the business long ago)

But not these. (they are dead) some are only dead for W7 on up or w10  only... now.  The deadpool is here. GONE from earth.(is not complete, and misses, merged then killed)

3com? (is now HP since April 12, 2010) and many drivers are now, not offered today. was huge in the win98/95/2k days.  Like the 3C905c  (I see only DELL support for only up to w2000)
All HP/3com pages are now GONE.

In most cases not running W7/10.? AS YOU SHOULD BE !
The best advice for a desktop (DT) is shop at and buy this card (PCI) it cames with a CD. (pop in the card , pop in the cd, load the driver done)  for a low buck fix.
PCI card or even USB to NIC adaptor $4, cables are sold today. 
 At NewEGG there are vast choices here, best choice PCI + 1000GB + windows 10.  (buy the card that supports xp to w10 and with a CD , or home page with all drivers there)!

StarTech ST100SLP  is $10 and runs Windows 95 and up. (to W10)

The same seller, sells USB wifi and USB Ethernet adaptors for very little cash. (do it and save all that grief working on some old near no  value PC ) 
What I do is run the scanner and see , omg there are 3 chips here that the makers are now defunct.  (the make a rational decision, junk it or , get the card or adaptor above)

Internet connections possible:
DIAL UP ( a land line POTS modem device)  56k  kbps speed V92 spec. Now obsolete.  $10 / month.   (POTS = plain old Telephone Systems
Or the above POTS connected to an Acoustic modem and old hand set?  We used these for years... funky and fun....
DSL  is a option offered by your DIAL up service provider. "requires special setup to work"  In most cases the router needs to login to DSL the correct way. 128 Kbps to 3 Mbps ( and loves to go slower if overloaded in the hood)
Cable TV, Modem , mine with 16 channels active does 200 Mbits/sec.  Download. (yes screams) ~$70 / month  ( I use and ARRIS modem SB6183. )  Best bang for the buck IMO.
FIOS , fiber to the home, there is no better service. (some homes have twin fiber) 500/500 Mbps  ($200/ month cost)  (or slower cheaper offered)
SATelite.  (a Dish)  internet say from Hughesnet  25 Mbps download and 3Mbps upload (new GEN)
3/4g modem wireless, card or usb adaptor, expensive and costly data chargers. (Like what your cell phone uses now)
WIFI, this is your router, doing this, and connects to your above services modems.  (Said in the context of you home)
Wired,  the best is Etherenet or  gaga-lan  wired Ethernet to your matching gigalan router. My page above shows you how to get this line working.  (and is best when doing MS updates for sure, or running PNP)
Cell phone tethering,,,( costly data charges or disallowed)
2 tin cans and  string,  no longer popular.

Realtek pain, the usa site FAQ says go to Twain site.    (mine is 8168 chip, via scanner scans called PCIe.)   I will demo here how I get said drivers.
 "where are the drivers is Q1"?
 "A1: (FAQ)
You may from our website ( ) download specific product driver."
We go there and see,,,
WYSIWYG, here. all drivers windows and linux.

HP PC's use lots of different COMM chips. WIFI and Ethernet chips.  Realtek,Intel , and others. Boardcom.

The router works perfect on other good PC.
The HP media kit was lost. (ask HP yet)
The HP F11 key is dead. (pc was slammed)
Microsoft servers for PnP are down. XP and VISTA and older are , so nothing new there...
The Device manager told you the driver is wrong. and update there fails.
On some PC's , there is  BIOS selection that turns off,  Ethernet and wifi chips.  (check that first)
You asked HP for help finding  driver,  they can many times ,dig them up from dead files, ASK and get lucky.
My page here is useless on new ultra  thin, PCs from HP now,  they deleted the Ethernet jack,  my page here does not cover, wifi, nor will I ever attempt to do that mess called Wifi ( huge variances in controls software exists)

I do not get paid a dime to show, any products.

version 1.  7-1-2017