My truck will not start. What do I do?

I have a 92 Ford Explorer but heres what happened. My truck started over heating one day, my buddy said it was my thermostat so I went and bought a brand new one and put it on there. Well turns out that that didn't stop the overheating. So im driving it as little as possible,and the other day it overheated and shut off, so I waited a lil bit and then stated it back up and got it to where i needed to get it. Well then after that every time i started it up water just started pouring out of it. so then it was the seal on the water pump. I went and got a new water pump yesterday and we put it on. (took us nine hours) and once we got it on we had to rush cause I had to be at work at nine and I called them and told them I was gonna be late and they kept calling me bugging me so i rushed a lil bit faster. Well we got it together and started it up and no leaks. So filled it up with water and went to work. The temperature gauge sow no signs of overheating but we was on our way to walmart and then my truck shuts off, starts smoking. So I took the few jugs of water I had in my truck and put it in there and waited like thirty minutes for it to cool down. Then drove it instead of going to walmart I just turned around and headed home. Well on my way home it shuts off again but this time no smoke was coming out so i just rolled it to where I can park it out of the way like someone else would do. Well my truck wasn't over heated this time but it wont turn over. Well turns out my fan was kinda loose but I don't think that would stop my truck from starting. I think it would just start spinning and eventually break. But I'm not too worried about it breaking I just need to get it back to my house. One of my buddies says it was my alternator that went out. Another said my motor probably seized up from over heating so much. My buddy that said it was my alternator said it probably went out cause I'm running a 600 watt amp off my battery. I'm not sure. I hope you mechanics can help me. Whats my diagnosis here?