back tire

Hi, My pit bike recently locked up the back tire from moving, while letting the engine keep running. Can only move it back and forth a bit but won't fully move, any ideas o why it won't go?

i have a mini bike :scooter:that i bought years ago and painted the bike and when it broke, i couldn't find any parts for it and here i am still looking. :out: I need to find parts for it and dont have that much of an idea of it i have searched around but cant find anything that will fit. I...