hi there your button stem has come unscrewed dont worry you dont need a new button it can be repaired but may be costly due to the brand (nots not an expensive thing to fix but they will charge due to the name)
if you feel confident enough you can do it yourself
unscrew the button so its off the stem it unscrews because the thread is worn then you need to rethread it the easiest way to do this is to get a tiny piece of copper wire you can buy it for and hardware shop.
cut a tiny piece off the wire with wire cutters and i mean tiny no bigger than a 1mm drop this into the hole in the button and rescrew it onto the stem this will rethread it and when you unscrew it now it will only come away from the case so you can set the time.
if you dont want to do this take it to an independant jeweller they are far cheaper than the big chain store
luke
August 2008