Why won't my car start? It is not a battery problem. Ignition key turns smooth

is it standard or auto

Have you tried starting it in neutral? Wiggling shifter also may help? I assume it is an automatic trans. If you get it started, take it to the shop and get the 'neutral safety switch' checked. It may just need adjusting.

Test for signal to starter solenoid when key turned to 'crank' position. Work backwards from there. System schematic and description would be really helpful to avoid guesswork and unnecessary parts replacement.