i car will not start, it turns over but it doesn't stay on. i took it to a mechanic and he said it was the distributor. so i bought it, but that wasn't it. what else could it be?

 

start with the basics, check for spark and fuel yourself, the guy who diagnosed it sounds like some half-assed mechanic

 

When you crank it, does it sound like it tries to start but then dies immediately? That happened to me, car died while I was driving. My ignition harness basically fried itself. Had to get it towed, but it was a $35 part and a very easy fix.

To check it:

Turn the key to the accessory position. Things like the radio should work. Now turn the key to the ON position. Things like the wipers and windows should work, but if they don't, then the harness is fried.

 

Patrick said it right. But, it may not be fried...just bad connectio. I had this problem awhile back. Took the ignition switch apart and cleaned it. Applied some electrical contact grease...problem solved. Hope that works for you as well.