Yeah....I know about such things...
Fortunatly it seems that I am the one lock challanged....and I asked a friend ( male!!) to see what he could do....and he fiddled and fussed and it worked.
If it works with a key that turns a latch and a little thingey flips out and locks the cabinet.....then there are no springs.
Call a locksmith...preferably some old guy that has been working with old locks for years....very often they have a huge collection of keys and can find another key that will work. Sometimes the keys just wear to the point where they no longer work.
Another tip....get some of those big decorative tassels and put one on every key for every chest and cabinet you have....keeps the keys from dropping down a floor register or just getting lost. I'm not crazy about the look...but it's really practical!
Linda C

When my mother moved here form the east coast after my father died....she put all her important papers in her desk, locked it and put the key in her purse and let the movers pack the desk.
Well...something happened on the move and her key no longer opened the desk, and it wasn't "old" maybe about 10 years!.
Anyhow...Mr. Arkin had a key that would open it...said the lock just got "jimmied" from the pressure of what was stacked on it...
Patience!! LOL!
Linda C

I have an old china cupboard and it does the same thing with regularity. I whack it gently right over the lock with my fist and it usually frees. In my case, it wasn't the lock sticking but the wood of the doors swelling just a tad. But, once I broke a key off in my cabinet and I did just exactly what Linda said, called a locksmith. I had him make me an extra key as well because those things have a way of getting lost.

Most of these old cabinets (and dressers etc.) have the same type of locks. They DO have a spring of sorts -- it is usually a piece of arched spring metal which rides on an eccentric. What this means, is that usually they are very easy to defeat (get into). If you put a little back pressure on the metal part that sticks into the frame, It will normally snap back to its unlocked position. Do this with a small (smaller the better) flat screwdriver, as you do not want to damage the wood OR IN THIS CASE-- BE VERY CAREFUL AS THE GLASS IN THIS CABINET IS VERY EXPENSIVE TO REPLACE!!. From the description you give -- the little lock may have broken internally -- that is if you get the key to turn -- if it is not turning in the socket -- then the door may be in a bind as someone earlier suggested -- good luck!!

I've had no luck, so I guess it'll have to be a locksmith. Thanks, everybody, for the input.

I am a certified locksmith and i have yet to see a lock that doesn't have a spring of one sort or another. While it may not have a conventional spiral spring it most likely has a U shaped piece of flat spring stock.

Most cabinet locks that were used on older furniture are what is properly known as a "Warded Lock". Inside warded locks there are thin metal baffles that prevent improper keys from turning. When the proper key is inserted the key has a slot that fits over the baffle, thus allowing the key to turn and the key hits a cam on the bolt that slides the bolt forward or back. Once you have the lock open you can see the spring to determine the thickness and width of the spring stock. You then take a piece of flat springstock the same size and cut it to length and bend it to match the original spring.

Most good neighborhood hardware stores carry the spring stock, but i doubt that you will find it in the large home supply stores.