Recently sound deadened my entire car. When I went to install one of my rear seat belts I noticed that it was stuck (would not extend any more length. Every time I tried to pull it out it rolled itself up more. Now it is completely rolled up and is totally stuck. It seems to be "locked" for some reason or an other.

 

I'm guessing something is touching the locking mechanism. Possible that the deadened material is touching it. This might be a pain looking through it.

 

Seat belt is out of car, completely rolled up and locked.

 

You need to stand it up perfectly vertical, and gently pull the belt out. The easiest way to do it, is just mount it back in the car and you'll be able to unravel it. There is a small ball inside the seat belt unit that locks the belt in place if the ball is at all out of place (rolled over car, stopping short, etc). I completely destroyed one of my seat belts to find this out, because I couldn't figure out how to unravel it. Once I saw how the inside worked, it made sense.