I have a 2000 Dodge Ram SLT ext. cab with the Infinity sound system and the right side speakers (all of them) stopped working and when I went to replace them with some alpine type s speakers I found that the small amp mounted on the stock speaker was damaged so when I put the replacments in they did not work either and the factory radio says on it (SP Error) what should I do.

 

IMO I think you should go ahead and replace all the door speakers and HU. You can get brand new door speakers (2 pair) for 100 bux and get a new HU for that or a bit more. In the end you will have better sound and something you can work on in the future