It happened to me a few times. I would do this to try and fix it. Even if it doesn't work its good to know how to do this...
Chock wheels so truck can't move anywhere if placed in neutral.
Get under the vehicle with I think its 1/2" socket but could be wrong on size
Follow your shift rod down and you'll see where it connects to the tranny.
Loosen those two bolts or remove them
Take the shift arms connected to the tranny and place them in neutral
Grab a screwdriver or small drill bit
This is hard to explain but up at the top of the firewall on your column, you'll see the two shift rods. You'll want to line them up to where you can stick that screwdriver or drill bit all the way through both of them to hold it at neutral.
now go back under the truck and tighten the two bolts back for the linkage.
This resets everything into a neutral position.
Now remove drill bit or screwdriver
Check to see if it works.
I attached a few pics with the drill bit I referenced inserted as well as the two bolts to loosen.