My car wont start at times

i have a 2000 ford escort zx2 90000 mles on it. at times it starts fine then next time u get in car nothing. ive changed alternators n serpentine belt but not help. safety neutral switch is bad. what is causing this to happen. battery has ben tested n i fine. when it wont start i have to have i jumped off n it starts immediatley.

Does the engine crank (turn over) but not start, or does it sometimes do absolutely nothing? Do you sometimes hear only a clicking sound when you try to start it? Please be more specific. Have you cleaned and tightened the cable connections at the battery? Are you certain the battery is good? How old is it?

Since you’ve changed the belt and alternator you must have somehow determined that the charging system was at fault.

“Safety neutral switch is bad.” There’s you problem.

If you know the switch is bad, why haven’t you replaced it? What is causing the safety neutral switch to be bad is years and mileage. It’s worn out, and needs to be replaced. Install, or have a mechanic install, an new neutral safety switch, and see what happens.