Fortunately most door lock repairs are simple. Use this guide to see if you can fix it yourself or if a locksmith is in order.
A sticky lock can be annoying. Try using some graphite powder in the lock. This serves as a great lubricant for locks. After squeezing the powder in, use your key a few times in the door to get the lubricant spread to the components.
A loose door knob can be problematic. It can cause damage to the lock when unlocking a door, and no one wants the knob to just pull out all together. The most common cause of a loose knob is a loose screw. As we turn the knob and pull on them, the screws do eventually work their way out. Just grab a screwdriver and tighten the two screws on either side of the knob to fix this.
It’s never fun when a key breaks in a lock. If the break is long enough you may be able to pull the broken key out with a pair of pliers. If this doesn’t work though, you’ll need to take the lock apart. Try to pull or push the broken key out with the lock apart. If this doesn’t work however, you’re only other option is to call a locksmith or replace the lock entirely.