Problem Solved
So, I got in touch with my mechanic today and he knew the solution. I'm writing it here so that others might use it in the future:
1) Getting the Vehicle to the Mechanic: This is a one-time fix to get the car started so you can drive it to where a mechanic can work on it. Take some WD-40 and spray it in the key hole. Put the key in and tap it like a nail with a hammer. Then gently jiggle the key and see if you can get it to turn and start the engine. I did this and it worked! However, don't take the key out as it will likely work ONLY ONCE.
2) Fixing the Ignition Key Lock: The problem in my case is that the ignition key lock was worn down, especially since my only key was a duplicate made from a door lock, not the original key (which i lost). Over time the ignition lock didn't recognize my key and needed to be replaced.
One other item: the 1987 Range Rover doesn't automatically lock the gear shift in PARK when the key isn't in like later models. So, there is no problem with the gear shift.
Hope that helps if anyone else ends up in my position. Thanks for all your advice.