If (PnP) fails the PC can fail totally (GPU dead) or any port on the PC can fail, or if Ethernet is dead, internet is now dead.
A Windows PC has what is called Plug and Play (pray) or for short ?  PnP.
First learn rule #1 , the chips in you PC must  have a working Software driver, for any major chip in the PC to work, sound, Lan, Wifi, GPU and all ports. (USB)
PnP is simple in basic concept, it simply is and engine that finds all the missing drivers via the internet. (
(MicroSoft.com) servers online  is the PnP driver catalog place.

Top cause of lost driver is #1:windows upgrades XP up to 10 or 2: or users getting drivers from evil websites (endless)
But wait you say,  my internet is dead,  and the Ethernet chip (or wifi) is dead now, because there is no driver for it.  (well that is simple get it from your OEM PC maker and uses sneaker net)

HP.com , Dell.com, Acer.com Asus.com, Lenova.com  (top +OEM's , yours can be different)
Do not get drivers from BUBBA-Gold-Drivers.com (a made up name if you get my drift)  they are either infected, useless and then they want money for bad drivers.  (money for trash! and no guilt.)

The steps for good drivers are simple:
  1. Fix the ethernet port dead first or Wifi working first. (get the driver from your OEM PC makers web site matching only YOUR PC MODEL and only the OS you run (Windows 10)
  2. Now the internet is working and amazing in a few minutes all chips and ports in the PC are all working, now, as MS  and your OEM  wants it.
  3. If not go to DEVICE MANAGER NEXT (in control panel) Look for dead devices and manually update the bad driver, done. But MS removed most of this feature in release w10 v2004 up.
  4. If the PC crashes get  a new GPU (video card or chip)  driver from OEM maker , the PC maker website or from AMD or Nvidia.com if that is what is in the GPU x16  PCI -slot.
  5. That is it most folks end at #2 and is the goal of MS and all OEM to end at #2 but some PCs fail for age or upgrades added.
  6. Age related failures are common over 10 years old PCs (2005 is the oldest PC Ive seen W10 run on correctly) XP PCs are trash, time to upgrade your PC.  See my Desperate sections below:
  7. Or is new GPU card that fails see this.
  8. USB ports dead (or driver for USB toys)

Sneaker net defined ( PC#1 is dead internet) so you go to PC#2 (good PC) and get the driver put it on  USB thumb drive and then sneak it over to PC#2) Then load that new driver  (Ethernet?) and bingo you get internet the sneaky way;.
Ethernet new wired is best until later get wifi going, an all the rest, now that internet is working.
The sneaker net still works in w10 v2004 up, use  the browse feature. Browse my computer, in Device manager, to the OEM driver is say, C:\my drivers OEM , folder. (hint get it and put it there first)
If the new driver.exe fails for say , wrong  OS  yours is w10 ,driver is W7, then do this magic, run the driver installer in magic MS compatibility mode.

Next is to fix them the hard way:  (first up is get the true chips real ID , called DEVICE ID's (ID means Identification)

The below is for the desperate.  I avoid the next example go use HWINFO64.exe free and safe.
 Missing drivers no matter how smart w10 thinks it is , and fails hard.
This is the super secret PCI-e DEVICE CODES , seen via properties + details. (no it is far from magic)
This are the secret IDs that MS uses to index and find a match in the link above.  THE DEVICE and OS are matched or it fails.
See VEN means vendor, and DEV= device code. This is the simple and direct way,,  but see a better way below.

Next I use the database scan , you look it up that way.
Once I know these codes, I can search online everywhere for drivers to match it.
I first look them up here:
Using the direct MS look up manually

We can look up the chip here in the databased to see if it even exists today.

The next examples are all using free software found on many safe web sites, and all my links are tested by me and virustotal.com

How to scan and sniff out , PCI identifications from chips.
This is one of the best, but sometimes it misses chips. (chip means DEVICE'S or means complex major IC's integrated circuits.)
#1 is Hwinfo32.exe (portable)  Or 64.exe  
This is Z270prime system.   100% free and safe !

The below I clicked (network) It is the Ethernet chip, and get the VEN = code and the DEV= code if this chip is dead or  wrong or corrupted.



There are other tools that are full of malware,  that I never link up.

  Sniffer 3 is retired now and the maker ended support. (the old one is at majorgeeks.com)


Why are my  chips (or ports or cards or USB ) devices dead , gee they are only 10 years old.
Well they did die, and when makers die the driver do too. (zero support, and zero w10 drivers made, means DOA)
Mostly XP, Vista drivers are now useless (to W10) W7 up might work if forced.

DEAD IS DEAD and WHY:  (no blood from a dead turnip)
The top chip makers are here today.

See a   list of old defunct chip makers,

The makers of  PCs send the drivers to MS,  and if he chip makers are dead this path is broken hard dead, the PC maker then tells you sorry no W10 support on this 10 year old PC. 

OK now that I know my super secret code  what can I do now, well look  it up dude (or lassie )
PCI CODE decoding is easy try these:
The goal here is to find the true maker of said chip then what chip it is  exactly "maker real name and chip model numbers"
I do this mostly only if my ethernet chip is dead driver, and if no w10 driver exist I add a Ethernet card or USB ethernet dongle, or go Wifi. (same ways, find driver if none buy the wifi card that does work on W10)


Use these alternate database tables and look them UP now, , after you  scan , your PC and learn VEN/DEV codes seen below.  (A good place to see links to PC ID repositories is here)

The above data bases convert the codes to real makers names. and model numbers of chips.
The a common chip is  10EC chip  is a Realtek  RTL8168E, Ethernet chip. (wired networks) one of many, and I ALWAYS fix ETHERNET FIRST. (do this first and Wiki working is 100x more easy)
Realtek does not offer driver, they tell you to go to your OEM for that. (Dell , HP, Asus, ACER, Lenovo as the case my be)

But first we look at Microsoft's solutions next.  Using the VEN and DEV codes as Microsoft search below makes for faster and more accurate look up of your driver.

Microsoft's  manual  driver search engine:   This is the PnP data base at MS.  New PCs use this and no user intervention is needed, and works automatically like magic.
But if not, you can go here and find  a driver any time you want.
 


One can go here and search many ways. (VEN + DEV) Or just VEN code or even makers name like Nvidia.
A chipset number, or sound chip #
Here is me searching now, at and into  MS driver servers Catalogs.




Here is my CURES section:
So very very simple buy a new chip, or card that is w10 supported. (new USB device, new LAN card or dongle, new USB sound card or dongle , new GPU card

Jargon?

ver.9:::::::4-15-2017, revised 10-10-2018 ( 5/2019) even less.  and less again. v8  , less again. and w10 fixes new.(v2004 w10 is now different