into a locked door. One with a door knob ,...tenant left it locked and took the key (after replacing it and not telling us or giving us a key)

I have never tried to force a lock with a pipe wrench. I don't know how easy or how destructive that would be. The door itself might be at risk depending on what gives first -- the metal lock or the wooden door.

If the lock is a Defiant or other cheap door knob (sorry, Defiant, I am not intending to disparage your quality, only to applaud your pricing!), using a credit card or drilling it out might be best (if you can't pick it). But you might want to consider bringing in a lock smith. See how much one would charge you to come out and pick the lock.

Yes, some tools used by plumber can be used to force the doorknob open by breaking the cheap type of locks. I had someone do it twice to laundry room door. You could see the indentations of the tool on the doorknob. First time it was to try to break into coin operated machines. Second time it was to use the laundry room sink as a bathtub. I added a deadbolt and that ended those problems.

Those events also caused me to switch to Schlage locks on apartment front doors. I'm no lock expert but I am fairly sure the Schlage would be much more difficult to force open with just force of wrench as compared to the real cheap locks. Of course the apartments all have deadbolts also.

Ugh...call a locksmith....bill against the deposit.

We stopped using locking door knobs years ago. Too often tenants will leave a key inside, step out, set the knob to lock using the little inside twistie thingie (no idea what that's called), and pull the door closed.... only to realize: "dang my key is inside."

But they changed the lock you say....

One reason I like Landlord Locks. Their tamperproof screws are almost impossible to remove without the special driver head.

We now check during our tri-annual inspections to see if tenants have changed any locks. If so, we swap them right back and bill them. Our lease forbids tenants from changing locks or adding door knob locks. $60 labor + cost of materials.

A little wallet training goes a long way.

Sid: "Too often tenants will leave a key inside, step out, set the knob to lock using the little inside twistie thingie (no idea what that's called), and pull the door closed."

The proper name for that is "the little inside twistie thingie." If you look at the engineering schematics on file with the patent office, that is the official name of that part.

"One reason I like Landlord Locks. Their tamperproof screws are almost impossible to remove without the special driver head. "

I use Landlord Lock's Tenant Resistant bolts, but some tenants have nevertheless managed to remove my Landlord Lock locksets and replace them with their own.

For ordinary entry knob locks, a body shop slide hammer is the fastest by far. Screw the tip into the key hole, one or two licks removes the cylinder. Then use a screwdriver to turn what's left.

a 3/8 drill bit just above the key slot will force all the locking pins to drop.

You might check for unlocked windows. 2 foreclosures I bought and had no key to get in, I brought my ladder, found an unlocked window, cut the screen and crawled in. Easer than drilling out lock.