Reversing the polarity on a radio may not blow a fuse but it could take out a transistor or a pre driver or both.
Diodes are like a one way gate to protect these components but all bets are off when you reverse the polarity.
Did you smell anything or hear a pop out of the radio when you did this?
The board in it may have surface mounted components and I only know one tech that has the equipment to work on these boards.
Look in your manual and find the radio fuse and don't just look at it test it with a DMM and if you don't have one replace the fuse with a new one.
If this isn't it you may have to source another radio.
thanks for your help bro...i found some posts around the web with the same situation as mine on a gto and the 2 guys just switched the fuse and the stereo turned on( hope so )
i didnt hear anything inside but outside i heard the fans turn on tomorrow ima check all fuses that everything is working.
i checked all the fuses inside the car and outside and they look good... everything else works except the radio but ima double check on wipers and check the laternator and fans...(forgot to check those)
tomorrow ill update to see i fix it problably help someone else in the future...

atriot: