95 Trooper Stuck in Gear - again!

95 Trooper, 4wd, standard, 6 cyl

I rolled backwards in my driveway -- with the engine off -- shifted into reverse (with the clutch) in... and when I started it, it wouldn't go into gear. Now it will only go into 5th and 4th. I can't get it into any other gear. I played around shifting into 2h and 4h, etc., no change.

The rolling backward part is signficant -- because this has happened twice before... both times it "jammed" after rolling backwards off a slight hill (because it's a hill, I just put the clutch in a rolled backwards...) but I didn't fix it either time. I took it to the shop and they said they couldn't find anything wrong with it -- the linkage something or the other was adjusted. Not sure. Hoping I can do it myself this time.

I know it's something simple, because no one charged me to "undo" whatever it is that had happened. I'm thinking they tapped something with a wrench and put it back in place or something.

Thanks in advance!
-RH