I just picked up skyrim again and it seems that I'm in the middle of the theives guild questline, with the objective of finding Mercer Fray. So I go through the dungeon and eventually come to my objective, the door to the statue room. I enter the room and I lose all control of my character. I can still use a few keys, but neither my tab nor any of my controls work. I'm stuck.

try to load a previous save before you enter the room. Outside the door wait for 31 days, then go in and see what happens !!!