Seat back will not lock back into position

My father-in-laws 1998 F-150 bucket seat is flipped forward (like when you need to get to something behind the seat) and will not lock back. Anyone know what has caused this? Has the mechanism broke? Whats the cure, junk ard seat, repair mechinism....? How hard to repair if its repairable?

No idea on that particular model...

Look at how the passenger side is put together, compare the two, you should be able to see what is wrong.