only one back window doesnt work, could it be a fuse?

It is more likely a power window switch or a bad or stuck power window motor. Sometimes you can pull off the door trim panel and smack the power window motor with a hammer and get them going, but if that happens a new window motor is in your future. Pull the door panel and test for voltage at the window motor while the switch is pressed. Sometimes you can even push the window switch ad watch the voltage at the battery go down a little. That usually tells you the switch is okay.