How about a photo so we know what you are describing. You'll get more suggestions if you show the lock detail and hinge detail. If you can move the cabinet away from the wall, also show us the back construction and how it is fastened.

Meanwhile, here are some actions you can do:

Using a flashlight, look into the lock through the keyhole. You may get a clue to its construction. Some of these locks are simple contraptions. Also, look at the key to get an idea of the shape of the internal part it fits. Make sure it was not a piece of the key that fell off.

On many simple cabinet locks, a nub on the key fits into a hole in the internal part and merely pivots this part. If that is the case, you may be able to move the internal lock part with an awl or other suitable tool that will fit through the keyhole.

If the back is a single piece of plywood, you may be able to carefully pry it off. If you are lucky, the back is made of several boards and you will need to remove only one of these boards to gain access through the rear.

If the back is put on using staples, the armoire may be less than 100 yrs old. If the back is put on with square nails, it is old.

We know nothing about its value as an antique, or if it is an antique or valuable collectable. You do not want to do anything that couls ruin the value of an expensive piece, however, if it a common cabinet, then destructive, but repairable measures could be used. For example, if it has glass in the doors, breaking out a glass might be an options. Don't break the glass if it a valuable piece.

Look obliquely at the glass to examine its flatness. The flashlight may help. If the glass is "wavy" (not perfectly flat to the eye), it may be antique glass and you would not want to damage that.

Thanks for your suggestions. I will go over to Mother's house later and try the flashlight and awl thing. This cabinet is not an old piece. It has no glass and the back appears to be one large piece. Also, the armoire has a white and gold crackle finish so if I damage that, it would be hard to get it back to the original finish. I'll also take a good look at the key and make sure it didn't break off. My deceased sister bought this piece about ten years ago at a high end furniture store. So obviously we are trying to keep it in tact if possible. Maybe I'll post a picture later. Thanks again.

If the above aDvice doesn't work, Try another locksmith. A good one can help. Not all locksmiths are created equal!

This post was edited by skatiero on Fri, Jan 18, 13 at 22:08

If the above advice doesn't work, Try another locksmith. A good one can help. Not all locksmiths are created equal!

A friend of mine lost the key to a 17th century breakfront in her move, so I jimmied the glass doors open with a small flat prybar, with her out of the room of course. The lock's bolt only grabbed the strike by 1/16 of an inch, so it didn't have to be pried very far or hard. So in your case if the lock's newer than 400 years it might fit too well to pry, but worth a look.
Casey