Toshiba Laptop Wifi wont work.

Hello,

Hello, My laptop's wifi isn't working. Any tips? It is a Toshiba Laptop with AMD A8 processor, it has been not working for over a year. The wifi will connect, but nothing will work using wifi, I have tried adding in a usb wifi dongle thingy (adapter?) and this too experiences the same problem. It also usually has the exclamation mark over the wifi saying it isnt working. Other devices connect to the wifi fine. Ethernet works.
Running windows 8 Enterprise.