I told her to go wait at the castle but I can't find her. Does anyone know where she's located?

Anyone?

1.) Don't bump. 2.) If you need to bump don't wait just 5 minutes. 3.) Let's work this out together, where did you leave her? Go back to where you left her and tell her to follow you, congratulations, you just found Serana.

in my pants.

Na seriously, load up an old save (you should ALWAYS have backup saves) find out where the last place you saw her was, and try to work out what happened from there.