Yea just replace your speakers. The factory ones don't blow and sound bad, they just stop working. I just had to replace mine.

 

Adding to the list.. Replace speakers.. Windows sometimes don't work just like the parking assist =(

 

I purchased my 2008 silverado in July, front door speakers didn't work either, so I replaced them with some coaxial 6.5" pioneers. That fixed the issue, but since the door speakers now had tweeters, it ruined the imaging.... To get them to work, you can cut out the cone and basket from the factory speaker and use the factory speaker rings as brackets for the new speakers. I ran that way for about a month, then went with Kicker 6-3/4 components. I also got some adapters so the speakers fit correctly, and replaced the front tweeters with the kickers..... MUCH better.

 

I made a thread on how to fix that. Just search nnbs window switch how to. I'm on my iPad or else I'd find it for you.