01 jetta cranks but will not turn over

replaced plugs,battery and battery cables, the car will crank but not turn over and depressing gas peadal while trying to crank has no effect. pump is working, could this be an anti theft issue?

Could be. But most likely your timing belt is shot. It’s not uncommon for the belt to fail when the car is shut off, so if your is in your driveway or garage, consider yourself lucky for more reason than the fact that at least you got home. If you had been driving the car when the belt failed, apparently major upper engine damage would have occurred as well. (I do not subscribe to this belief, by the way. I had a '92 Talon that experienced a timing belt failure while driving, and it was fine).

If you have not yet replaced the timing belt during ownership of this car, it is time to do it anyway, and it is likely the problem, Make sure you replace the water pump at the same time, because it must be removed to replace the timing belt. Labor is your big cost replacing the timing belt, as the part itself costs about $20. The water pump costs about $60 for the part, and no extra labor is involved to replace the existing part with a new one.

The car won’t start after battery replacement means the timing belt is broken? A bit of a stretch. If the belt were broken the engine would crank unusually fast and wouldn’t sound normal. It is far more likely an anti-theft issue if your vehicle is equipped with an anti-theft system. Not really enough details here to tell.

(I do not subscribe to this belief, by the way. I had a '92 Talon that experienced a timing belt failure while driving, and it was fine).

I understand some cars have timing belts, but are not interference engines. So they can blow a belt without damage to the major engine parts.