'96 XJ 4.0L inline 6.

It won't turn over, tried jump starting it, replaced the fuel filter, distributor cap and rotor, coil, caved and got a new Optima... The fuel pump is working.

Any ideas?? Drove it Saturday night and woke up to a dead car 8 hours later. Ran great the night before...

 

Does it crank over at all? If yes, possible bad crank sensor. If no, I'd first try jumping across the starter leads with a screw driver. If that doesn't work, check your cables for corrosion. If you're good there, it could be a starter. Bribe a friend to tap the starter with a hammer while you try to crank it. If it cranks then, it's definitely a starter.