I had the stock radio in the blazer and the driver door and passenger rear door wasn't working, soo i put a new radio in and the same speakers dont work all others do.. what can cause this just bad speakers wiring hurt?

 

Have you taken the door panels off and physically checked the connections to each speaker?

Sounds like you tried to fix something that wasn't broken.

But the stock head unit is junk so good thing you got that taken care of.