I have a troy-bilt riding mower and it sometimes gets stuck in gear and wants to keep moving whether it be forward or backward.

With out any No# to look up your exact linkage a number of things could be going on there.

The input and Output shaft bushings are worn..
Rust on the input shaft. .
Shift detent balls over adjusted

Just guessing

It could be some minor adjustments.

If you could post the numbers

Make
Model type

It is a Troybuilt model 809 garden tractor, when it is creeping forward it is really hard to to get out of gear. Wife tried to stop and it slowly ran into tree, I thought it was funny but she didn't. For safety it needs to be fixed.

I need

Model
Type
Code

Off the engine
If you see a chassie No# get that.