1999 Bonneville w/ Supercharge won't start :(

Sounds like a bad ground. Do the headlights always turn on without the ignition. Check where negative battery cable contacts motor or frame. Make sure the contact is clean and shinny without rust or grease. The supercharger belt is separate and shouldn't be preventing the starting problem. I drove my own 2000 a full year before I discovered my belt was even missing.

Yes lights all (inside & out) all working and looking great. Even changed a fog light that was out the same time the alternator was replaced. Will check the negative battery cable. Would this cause it to sometimes start & sometimes not?

If the lights are bright then their has to be ground. But check it for bad or loose contact. If this fails then either your ignition switch or your safety neutral switch may be going out and just acting up when it feels like it. Next time it doesn't start shift your gear lever up and down and see if it doesn't start right up.

I tried starting it in neutral and that didnt work. I replaced my ignition switch because of a broke wire, security light never going off, and would not start at all so won't be the ignition switch. Will check the wire though.

I had this issue just got my car back yesterday it was the ignition something about the chip in the key or something Im a female my dad had done for me

i can not move the gear at all , it in park but i can not move it seen like it stuck. But the light on, horn blow but i just can't start it.