It sounds like something isn't working right. Without more information, That is the best answer I can give. I have seen malware block internet access. You can download and run winsockfixxp.exe if you are running xp or older. You can open a cmd prompt (run as administrator) in Vista or 7 and type "netsh int ip reset" at the command prompt and hit enter. Then reboot the computer. I have also seen problems with a motherboard preventing ANY PCI card from working. However, in that situation, a USB adapter worked.
something is blocking any nic card, usb to 10/100 adapter or even wireless network adapter from working. none of the installs will work! i can't get on the network.....
I had the exact same thing happen to me a few days ago. Absolutely NO network device could run in Windows.
I made a total backup of the system for later analysis and performed a restore point rollback to about two weeks ago.
The restore point completely fixed the problem. Now I will take some time and learn what caused that problem and a solution to it.
Official advice: Do a system restore point made before the problem started. Make a new restore point immediately if everything now works properly.
Sounds like you picked up a virus. Even if you catch and delete the virus, it often affects the operating system in some way before it is effectively removed.
By rolling back the system to a date prior to when the virus was picked up effectively cancels any system change the virus might have created.