Why doesnt my car start?

ok I have a 1993 nissan 240sx which runned perfect I turned it off after going to the store then never wanted to start again when I turned the key to the on position I heard a clicking sound ok when I attempt to crank it the car didn't do anything so I pushed started it and the car turned on and stayed running.so I changed the starter and the battery and still nothing it keeps making a clicking sound and doesnt crank so I pushed started it to take it to a machanic but this time the engine shaked a lot and the car turned off after about three minutes can anybody tell me what is wrong with it I could really appreciate it

Its most likely more than one thing wrong with your car..

Most probably the timing belt and the alternator.

the battery is probley dead or something.

Sounds like Timing Belt .

might be the alternator.if some electrical parts aren't working and some are.then it's the alternator.

cuz its busted..DUH.

well HHHMMMM let me think sounds like you have an issue with a ignition coil or a starter relay of some sort maybe you have an issue with a wire loose on your ignition system it's hard to tell without looking at the car?????

Rapid clicks weak battery. Look for little bits of plactic rubber on the drivers floor of the car there's a grommet that pushes on the clutch switch it crumbles away after ten years. That will not let the starter work. Roughness Dying that's a whole other thing. Check those then Ask another queston I'll watch

Is it over heating?