Umm....OK. It's hard for us to help you out if we can't completely understand you.
If you turn the key, it won't crank. OK - got that part.
If you "jump" the ignition, it cranks. Alright - what do you mean by "jump"? What are you jumping and how are you jumping it?
Could be any number of things: Dead battery, starter relay is bad, starter solenoid is bad, starter motor is locked up, ignition switch is bad.
Detailed information on what exactly happens and what you are doing to it goes a long way.