Won't drive when in gear

I have a 98 Toyota Camry with 91000 miles. My problem is that when I put it into gear (from P to D, or any other gear for that matter) nothing happens. The car won't move in reverse or forward. It runs fine. It doesn't make any funny noises. I still have to push the button in to switch the gears, but it's real loose when switching from p to r to d to 1...etc. Before this happened, it would switch to different gears if you bumped the gear shifter, without pushing in the button. Any advice? I desperately need it fixed!!!!!!!!!!!