Assuming that I can't just unlock the door and leave, and that this room isn't important to me or anyone I care about (ie: no one's going to care if the room or anything inside it is damaged, and eventually I'll get to leave the room and never have to return), I'd probably indulge my penchant for violence and start shadowboxing, as well as punching walls and smashing stuff, aside from anything that I'd consider to be useful/valuable. (like the guitar) but first, I'd fold and put away all the dirty clothes so that they're not in my way.