Hi
Operation of the Digital Crown can be affected by substances like dust. Should it become stuck or stop operating as expected, it can be cleaned by following the steps 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), 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: