Try:
"SELECT id FROM p_msgs WHERE (from_player_id=14 AND to_player_id=15) AND (msg_title='gbhjhghgjhgjgjhgjghj' AND msg_body='gbhjhghgjhgjgjhgjghjgbhjhghgjhgjgjhgjghjgbhjhghgjhgjgjhgjghjgbhjhghgjhgjgjhgjghjgbhjhghgjhgjgjhgjghjgbhjhghgjhgjgjhgjghjgbhjhghgjhgjgjhgjghjgbhjhghgjhgjgjhgjghjgbhjhghgjhgjgjhgjghjgbhjhghgjhgjgjhgjghj')"
If you don't quote the text, SQL assumes it is a variable name of some form.