As for the drivers not being installed then you are saying that the device is either disabled or has an error icon next to it showing that it is not working (in Device Manager). If that is the case what is the MOBO, and/or network card name and version, and/or if a purchased machine the product name of the PC.
What OS are you running also?
You say that you can connect to the Internet but can't access it. Perhaps under Windows 7 the 'home network' is not setup for public access? This will prevent access to the internet from the PC. You can search on how to fix that nightmare.
Also,
Assuming your are running Windows;
Are you using a wireless router or wired to a router or bridge?
Let's see if you can communicate with your devices.
Can you ping the router? Open up a cmd shell (Type 'cmd' in the start window. Then in the DOS shell type 'Ping [your router's internal IP address]) Try 'ping -n 50' . This will ping the router 50 times. There should be no errors or timeouts. If there are then the problem is between your PC and the router. Perhaps a cable between your PC and the router or PC and bridge (if using a bridge or external network device, or router to cable modem?)
If the ping can't reach the router it could be that the PC's network is no longer communicating because of settings.
Try to ping something on the Internet, IE. 'Ping Disney.com'. The time in milliseconds will vary but you should see nearly 100% return. If you see anything below 97% the problem is not in the computer but somewhere in the 'path'.
Hope that gets you started and onto a solution.