There are four different methods locksmith suggests for opening door knob without a key. In the first method, use a credit card on a spring lock, this method is applicable on spring locks, not on deadbolt locks. In the second method, insert a narrow screwdriver inside of the knob, and with a right twist the lock gets open. The third method is, to pick the lock with Allen wrench and paperclip tools. It is a complex method that requires much attention. In the end, when the above-mentioned methods fail then you can choose a destructive method. A destructive method is dangerous, can destroy the whole door. Locksmiths know how to open the doorknob without error. Locksmith Houston is best at unlocking different locks, by using basic tools. They always avoid going for destructive entry methods.