Why is my car heater not working?

I have a 1986 Chevy Caprice in July i had a AC compressor, oil and freon put on it. Once we went to start the car the starter went out and the car wouldn't crank. I had to wait about a month before i could afford to get a new starter. So once i got the starter put on the a/c didn't work at all, it blow but no cold air, the heat don't work and it worked like HELL before and my defrost is not working. What went wrong and how do i fix it?