2001 BMW 325 seat recline

The worm gear may be stuck. Have someone flip the switch and see if you can see the worm gear try to turn. Sometimes seats get stuck. If you can get to the worm gear without using the switch see if it will turn using a pair of pliers, Don't try on the threads themselves but on another part of the shaft. If you are not able to get to the worm gear then you will have to take out the seat and free it up that way.

This is a common failure and will possibly require replacement of the worn gear(possible but difficult) or replacement of the entire seat base(easier but more expensive) Either way you will need to source the replacement parts and most yards will sell you the seat base and you can then either replace it yourself or outsource the labor.