lock cylinder will not turn o on 1999 Lexus GS400

lock cylinder wont turn on the 1999 gs400 lexus, i try to see what the problem could be by pulling off the cover on a 1998 lexus gs 300 from around the key and both cylinder lock and wont turn, help

Asked by for the 1999 Lexus GS400
maybe your lock cylinder is broken
Could be a key problem.