No sound at all. Confused.

Can someone please explain to me what's wrong with my speaker/ radio/ amp? Whenever some one (my bf) tries to explain my situation I instantly get confused. Here we go. So I myself recently discovered that my sunroof was leaking water into my amp/ sub behind my drivers seat. Apparently it is a very common problem. Now my bf is telling me that I can just buy a new aftermarket radio (the part that you insert a cd in), but others are telling me I have to replace the entire system sub/ amp etc is that true? I removed the amp (it looks like a box) and was told to test the fuse, which I couldn't find. I was also told to smell it to see if it smelled burnt which it didn't. My stereo used to crack now there's no sound at all. A couple of days ago it worked for about five seconds and nothing since then. It is a jbl 2C200. So can someone please tell me exactly what I have to do to get music going again. Thanks a head of time.

2003
Tiburon
Infinity sound.