i HAVE A 97 AND 98 DISCOVERY AND THE KEY WILL GO IN AND OUT BUT WONT TURN IN EITHER ONE. I TRIED WD 40 IN THE KEY CYLINDER AND THAT DIDN'T WORK. ANY SUGGESTIONS?

 

Seems stupid, but are you using the right key for the right trk? Did you try turning the key over? Sometimes double sided keys wear out on one side and then that side wont work.
Also try slamming the gear shifter into park, if it is not in park all the way it wont let you turn the key.

 

Also, try turning the wheel to the left, sometimesmy keywon't turn and the steeling wheel position is the cause. I don't understand the mechanics but it seems to work.

 

Yes, the steering wheel lock is bound up. Wiggle the steering wheel back and forth as you try and turn the key.