Mechanic Q: My car's wont shift into gear.?

So I was driving my 2002 chrysler sebring LXI with about 120,000 miles and it just stoped moving as I tried to accelerate. It's weird because it acts like it wants to shift when I throw it into gear but then goes back to idle and doesn't move. I dont know if its the transmission or the gearbox maybe the torque converter or the clutch assembly? Help please!