Problem

Hi,

I bought the car from an auction without checking first. When I drove the car, it drove fine but stopped randomly with engine shut off. Gave it a jump and started back up but died again, I figured the alternator is bad and the battery isn't charging. I took it to the mechanic and he told me the same thing, and got the alternator replaced for 378 dollars. The car would crank for a while before starting. It took good 5 seconds of cranking before the car starting. Today I started the car and it died on me again, when I pressed the accelerator, the car would die. I started again and let it run for 5 minutes and it drove fine. ( I think the engine oil needs to be changed). Drove the car and it drove fine, I drove for about 50 miles going to school and coming back it was driving fine. Suddenly the air conditioner stopped working, I try to turn it on but even the fan won't come on. I stopped the car in a parking lot, try to turn the defrost on, something to make the air conditioner or fan work. I start hearing a weird noise in the back speakers of the car. I turned the car off, turned it back on and it wouldn't start. It keeps crankning. Click click click. It won't start.
I am not sure what I should do as I have already spent so much money on it.