Welcome to JustAnswer, I'm Neal and I am here to assist you. Please feel free to ask follow up questions, it is part of the process.
I assume the fluid level is good? That has been checked?
Then it is just going to be a problem with your linkage, it was either damaged or there is still debris stuck up under the truck ocstructing it.
A visual inspection would be the first thing to do.
But there is notthing under or ocstructing it
I would really be checking the linkage, it's strange but I don't know what else it could be.