Why does the sound not work?

My Denon hasn't worked for a while i recently have a reason to look into it. When everything started going south it popped the speakers that it was hooked up to. Now if you have it turned off for a very long amount of time you can turn it on and it will play for a minute but then the sound shuts off and the speaker makes a squeeling sound. The power works fine the only problem im having is that. If you aren't sure can you point me in the direction of somewhere i could take it to get it looked at?