wont turn over!

Ok so I can't figure this out for the life of me. My XJ will not turn over. I thought maybe it was the solenoid or starter so I tore it out and tested it and it worked fine. Just to see what would happen I put a different starter and solenoid on it and what do ya know it starts right up. I drive it for the day and a few hours ago I try to start it and it won't. I hammer on the solenoid for a little and get it to start. I shut it off and try again and it won't now and hasn't all night. I can't figure out the problem for the life of me! Any ideas? Oh and I have a button starter so I bypass my nss.

give us some specifics on your rig...year, motor, tranny etc...

How are your cables? I had a bad neg cable, it would start cold... As soon has i drove it, i could not turn it off, NO re-start every time...Place too start

Its a 92 under the hood, straight 6 eh I'm not sure on the tranny ill check tomorrow. I also just noticed IV got a really bad spot on my negative cable, ill pick one up tomorrow and prey its that simple! Thanks for the help!

Connections and grounds ALWAYS suspect for intermittent stuff like this.
Clean all battery connections. Replace cables as necessary. Remove engine grounds and clean everything with wire brush, reassemble.

If it happens again, take a multimeter and look for 12 volts directly at the starter. If it's not there (likely), then start working your way back to the engine!