upvc door-key won't go in the lock

[jim24w]

The door will lock and unlock okay from the inside but I am unable to get the key into the lock from the outside. The handle on the outside is a little loose but perfectly functioning. It is a standard lock with a yale type key that requires you to lift the handle before locking it. Any suggestions?

[welsh brickie]

on the door mechanism there is a cross head screw that may need tightening and spray the rollers with wd40,if the problem persists then change the lock (euro cylinder) all you do is unscrew that screw and wiggle the lock with the key inserted and it will pop out