Replaced timing belt, engine wont start on 2001 Dodge Neon

Have you checked for diagnostic fault codes? When you have an engine problem, please list the engine size and whether it's a single or dual cam engine. Have you rechecked the belt timing?

If this is the single cam engine, check for a sheared off dowel pin between the camshaft and sprocket. That will let the sprocket turn a little which retards the cam timing just as if the timing belt was off one tooth. At one tooth off, (or the equivalent), the Check Engine light will turn on and the fault code will be "cam and crank sync". At two teeth off, the Engine Computer will shut the engine down to protect it. You will still have intermittent spark at some plugs. At three teeth off, the pistons will hit the valves and bend them.

If the original belt broke while the engine was running, the valves will be bent. You can verify that with a compression test or cylinder leakage test. The engine will sound unusual when you're cranking it too.