I cannot open rhe back of a 3950 lady watch DKNY

If you look at the movement inside the watch it should be possible to find the movement number (you might need a loupe or magnifying glass to see it clearly) and name (e,g, Seiko-Epson, Miyota etc.)
If you can supply that information I can tell you which battery it requires.

please see attached website.www.esslinger.com/watch-crystals/

Go an purchase where it is. What else to do?

David only a professional can fix this or replace it.

Usually you would have to press really hard to get the case back on the watch, especially if it's a large dial. If you still can't get it back on, I suggest taking it to a watch repair person. They might charge a couple dollars or do it for free. If you prefer to do it yourself you can purchase a watch tool presser for around $15, just be carefull when using the tool , make sure you have the right size dial and you are all set. You can try it on a cheap watch first, just so you can practice. I hope this helps! Marcelo

It is probably replaceable. Try to locate a watch repair shop or and jeweler who repairs watches. If they don't have one, then contact DKNY directly.

mcdevito75 here, It"s possible the battery could be so ever slightly loose, or the battery could be weak and need changeing. Also possible, the quartz mechanism could be going bad and movement of the watch while wearing it keeps it going, with the watch off your wrist and at rest, it's just to weak to keep moving on it"s own. Best Bet is to look for a small watch repair shop in your area and have them check out your watch.

DKNY is typically a quartz movement and doesn't have a "winder". I believe the part you are referring to is the crown. The watch may have stopped working for several reasons. The first three things I would suspect is that the battery died, the watch is in the set position, or the movement was damaged when the crown was coming off. If the watch is in the set position then pushing the stem in will cause the watch to run. The next thing to do is to replace the battery since it is only a few bucks. If it runs then you can replace the crown and your set. If it doesn't run I would suggest replacing the movement along with the crown and that you will have to price and see if it is within reason since this type of repair wont be covered under warranty.
Depending on the model of DKNY you may have to go through DKNY for the part. Remember that they are manufactured by Fossil. You could save yourself a lot of time by going to your local watch repair shop.

Thanks!

Hi, you should be able to get one from a watchmaker

I suggest calling DKNY customer service @ 1-800-231-0884 This is their return or repair department they should be able to help with links for your watch.