I drop mine ,screen crack then stop working where can I get

Hi

Apple Watch is not user-serviceable and Apple does not offer a screen repair or screen replacement service for Apple Watch.

Your Apple Watch will instead need to be replaced. It may be eligible for replacement via chargeable, out-of-warranty service or via AppleCare+, if previously purchased.

Contact Apple Support (mail-in service may be available, if required), make a Genius Bar reservation or visit an Apple Authorised Service Provider to establish your available service options:

• US: Apple Watch Service Answer Center - Apple Support
• Elsewhere: Apple - Support

Service pricing for the US, for example, is detailed here:

Apple Watch Service Pricing - Apple Support

In the meantime, note that Apple advises that you should not continue using (or trying to use) a damaged Apple Watch.

Make an appointment at the Apple Genius Bar for service. If you need to find an Apple Store - Find a Store - Apple.