So are you saying nothing happens when you turn the ignition switch to the Start position? The starter motor doesn't work to crank the engine?
If the starter motor isn't cranking, there are three test points on the starter you can measure for voltage to isolate the problem,
On the starter motor in the photo below, the big top copper bolt always has +12v on it, it is connected directly to the battery. The bottom big copper bolt is what provides power to the starter motor itself. The skinny wires that connect via push-on connector come from the starter relay inside the Power Distribution Center. When there is 12v on the wiring from the starter relay inside PDC, that energizes a relay inside the smaller cylinder on top of the starter motor. That is what connects the +12v on the top bolt that connects to the battery to the bottom bolt that powers the starter motor itself.
So see if you're getting 12v at the lower big copper bolt when the key is in the Start position. If you are seeing 12v at the lower copper bolt when the ignition switch is in the Start position and the starter motor is not working, the solenoid is bad & the starter needs to be replaced. If the starter solenoid isn't getting 12v from the small starter relay inside the PDC, it could be a bad ignition switch, bad starter relay, or bad wiring, or the clutch interlock safety switch is defective. Depending on your TJ's model year, you can disable the clutch interlock safety switch by either inserting a fuse into the fuse panel behind the glove compartment, or moving a cable connector above the driver's side footwell. Which method works for your particular model year will be explained in your Owners Manual.
This pic is very similar to your starter but isn't exactly the right model... but it's close enough for this purpose.
You can also jumper the two big copper bolts with a screwdriver to see if that energizes the starter. MAKE SURE THE JEEP IS IN NEUTRAL
& THE PARKING BRAKE IS ON IF YOU DO THAT.