So I was checking all my fuses to see why my ac wasn’t working but that is a whole different problem. But when I tried turning back on my truck the key wouldn’t even turn and the theft light was on and flashing with a beeping noise. I’m pretty certain that all my fuses are okay and functional. Can anyone help?

 

Reads like your key cylinder is broken
There in "electrical" reason the key wouldn't turn in the lock, that's all a mechanical linkage

There are no electric locks or solenoids in that area of the steering column
Try turning the steering wheel a bit one way then the other way while turning the key, steering lock rod can prevent key from turning