Router or Wireless Internet Adapter?

[poofusnoof]

I have my iMac hooked up to a Wireless Internet Adapter via USB Port.
And I have my router hooked up to the internet and my PC is connected directly to the router.
All was working GREAT, and then about a week into using this..it just stopped working.
My wireless router couldnt find any wireless signal.
I used to be able to pick up another signal from my neighbors..but now that wont even show.
Is this just a problem with the Wireless Internet Adapter? .. Or is my router messed up.
I did put my computer .. right next to the router.. and it still didnt pick up a signal..and the routers seems to be working fine...

Any Input Is Appreciated.
Thanks!