Too options...
either your shift cable slipped off... first pop the boot cover and make sure both cables are attacthed to the shifter, then check to make sure the cables are still connected to the shift tower on the tranny.
If both of those check out, then your looking at option 2...
This means your shift tower bolt seared off in the transmission which can sometimes be a fairly easy fix, or other times it can be a PITA and require removal of the transmission.
Is your car stuck in neutral, or in 2nd/3rd gear? If your shift tower bolt did sear off, and your car is stuck in neutral, then you can pull the shift tower with the tranny in the car. Then you have to find the seared off bolt and pluck it from the inside of the transmission! If your car is stuck in gear, then it is alot harder, and sometimes impossible to pull the shift tower with the transmission still in the car.
Let us know what you figure out, and I am local, so shoot me a PM if you need some help.
Good luck!
Jeff