Help Lock Knock

Syntax cast 'knock'
       cast 'lock'
 
The knock spell opens stuck, barred, locked, held, or wizard-locked
doors. It opens secret doors, as well as locked or trick-opening
boxes or chests.  In all other cases, it opens locks or welds--although
the former could be closed and locked again later.
 
The reverse spell, lock, closes and locks a door or similar closure. 
 
See also unlock, picklock