Can someone help me fix my wireless network?

Alrighty , I have a wireless network in my house. the wireless computer is the one in my room, the main computer of the house is in the den. About a week ago , the one in the den (call it comp 1) severly slowed down, when online then stopped working all together, while the one in my room (comp 2) was working just as it always has on the internet. Can anyone give me instructions on how to fix this problem? I have already called my service provider and they said it could be the router , but i have gone through two brand new ones with the same results. so that cant be what it is . step by step instructions would be greatly appreciated.