It is possible, though unlikely, that your shifter cables are undone somewhere between the shifter and the bellhousing.
Start by looking underneath the rubber boot of your shifter, and see that both cables are connected to the shifter.
Then look under the hood at the bellhousing, just between the battery and the firewall, slightly lower, and have a friend row through the gears.. watch for both cables to move in both directions, freely. If they don't they are undone, probably between the two locations, underneath the car, about where the firewall starts. (cables come from the shifter, through the firewall...)
Otherwise, you may be looking at a transaxle work.
Hopefully, if you are, its the shift tower that's broken. It woul dbe the cheapest, and easiest to replace (can be done with the engine in the car, from the top) and relatively quick. Other transaxle work would be more in depth, and more expensive. Suggest contacting Terry Haines, of HMS motors, if you decide this is a transaxle problem.
Ray