I just recently took off my shower head to clean it.
I put it in a pot of hot white vinegar and diluted it with hot water on a stove top.
I then took it apart and then placed it back in the vinegar/water mixture in a pot on the stove. Before I put it back together, I tried turning the shower head to change the spray setting (for example; mist, jet, etc) and it wouldn't turn. I put it back together and tried again, and it's still stuck. Is it fixable?

I also have a chrome shower head, I believe.
& its not a handheld shower head.

Probably not. Probably has plastic parts that distorted from heat, all depending on how hot you let it get? If you didn't let it get to hot, put back in solution try again.