1997 Transmission problems?

A few days ago, I went to take the car out of our driveway and the car wouldn't shift any further than Reverse. Last night it wouldn't even shift out of park. I was wondering if anyone had any advice. The car has only 55, 000 miles on it. It was originally my grandmother's. I'm not sure if she ever took it in for a transmission flush or not. I'm guessing probably not becuase when i got the car 2 years ago it only had 12, 500 miles on it. Does it sound like all it needs is a tranny flush or does it sound more dire. Please help.

it sounds like there's just something wrong with the shifter or shifter interlock

I can move the shifter, but it's like the gears don't want to switch. I move the shifter into anything but park and it's like it doesn't want to acknowledge the change.

oh, ya, then your transmission is toast, typical AX4S failure

Two kinds of Taurus owners: ones who have had transmission failures, and ones who WILL have transmission failures.