Macbook won't connect to Wifi ; Not a router problem

So I have the black Macbook that came out in 2006/7 and it has stopped connecting to the internet. I have been having some random issues with it over the last couple months like some pages just stopped loading or it would take an extra long time to connect. But now it isn't connecting at all, to any Wifi. I have my PC connected and my iPhone too, but the macbook won't connect at all. I have tried it with 3 different routers and it all the same thing, it loads for about a minute and then the "!" pops up saying "no network connection" I have tried resetting the mac, turning the airport on and off, and forgetting the remembered networks. Nothing seems to help, and it has to be a problem with the Macbook itself at this point because it won't connect to anything.

Any help is appreciated

How about if you hook it up via an ethernet cable? Does it work then? If it works that way, your airport card has probably failed.