I just want everyone to know that Valstein suggestion below worked for me to solve my wireless controller.
"I am also having this same problem, and just like any biped with any amount of common sense, the first thing I did was hit the Sync buttons. My problem started directly after a momentary power outage. The thing is, my Xbox and all of it's components are hooked up to a surge protector. If anybody who sees this comes across a fix, please quickly make an account here if you don't already have one, and help us out. Theres atleast 20 threads on various sites from people with this exact problem, and not a single one of them ends in a fix."Valstein