Help. My PC cannot connect on internet

I have a desktop, I used recover CD to reinstall system. after that, I can not connect to internet. Following is what I tried.

1) uninstall the network adapter, (computer-management-device manage ) then restart computer. Failed

2) reinstalled the driver of network adapter. I used recover CD. The computer told that it can not find the driver in CD(weird). I also tried to download one online which specifically matches my PC, but it can not be installed on the PC(weird again).

I don't know what should I do next. Does anyone have experience? Thank you.