Please help

I had found Thorne's ID and therefore gained access to the lab, but at one point when I exited and tried to get back in, the door was locked again, and because I already used the ID, I can no longer get in. Help!

Face the pipes in the corridor and the click on the bottom of the doorframe to the laboratory near the left-side. That will take you into the lab but you'll need to do it each time you want to go back in.