PC network problem ... Please help

[Ilwrath]

As Wayne said, checking the BIOS is a good start.  It helps narrow if you're looking at a hardware or software problem.

If we're looking at software (the items show up in BIOS) when in Windows Device Manager, do you have any items with yellow (!) or (?) on them?  If so, try deleting them and rebooting.  This will force Windows to redetect and reinstall their drivers.  

What version of Windows are you running?  There may be some additional steps to help...

[Ilwrath]

Ok, for Windows XP, make sure your 'Plug and Play' service is set to Automatic and is started.  If that thing isn't running properly, it'll cause all sorts of havoc (usually more with sound cards, but also with network cards).  Also check that the 'Network Connections' service is started and running.

And, just to confirm, you have no yellow (!) or (?) and no disabled devices (red X) anywhere in device manager.  (Not just not under the "Network Adaptors" branch, but none ANYWHERE, right?)  Is a 'Network Adaptors' branch even being displayed?  If so, what's under it?  

And, a next debugging step...  If you still suspect software, as Zac67 said, try a BartPE or Linux Live CD.  If that detects a network card properly, you know it's software.  Might be time to reinstall Windows.  

If the live CD does NOT detect the network card, though... It might be time to start examining why the hardware isn't being presented to the OS.  (Probably a hardware fault or misconfiguration.)

[Ilwrath]

Glad someone's onboard network is working.  My onboard Intel Pro 100 / VE decided it would kick the bit bucket.  I was just working along and blam, reboot, and then my physical media was detected as 10/Full.  (And still stayed as 10/Full as I unplugged the cable...)  Intel Pro diagnostics fails with a status of physical loopback failed.  

Time to pick up the cheap PCI Gig E card for me, now.  (I'd been wanting to move that machine up to 1000TX, anyhow.)