Hi
Operation of the Digital Crown can be affected by substances like dust or lotion. Should it stop operating as expected, it may help to clean it by following the instructions here:
Use the Digital Crown on your Apple Watch - Apple Support
If the issue persists after following the recommended procedure, I suggest that you contact Apple Support (mail-in service may be available, if required), make a Genius Bar reservation or visit an Apple Authorised Service Provider with a view to arranging for your watch to be inspected and, if recommended, serviced: