Hi
Apple does not offer a screen repair or screen replacement service for Apple Watch and Apple Watch is not user-serviceable. The watch will instead need to be replaced.
Apple's Limited Warranty covers issues due to defects in materials and workmanship, but not due to accidental damage.
If you have previously purchased AppleCare+, then the issue may be covered as one of up to two claims for accidental damage, each subject to a service fee / excess. Otherwise, your Apple Watch may be eligible for replacement via chargeable, out-of-warranty service.
Out-of-warranty service prices (and AppleCare+ service fees / excesses) vary by country and by Apple Watch model. Pricing for the US, for example, is detailed here:
Apple Watch Service Pricing - Apple Support
Contact Apple Support (mail-in service may be available, if required), make a Genius Bar reservation or visit an Apple Authorised Service Provider to arrange for your Apple Watch to be inspected and to establish your available service options, timescale and any cost:
- US: Apple Watch Service Answer Center - Apple Support
- Elsewhere: Select your country for Apple Watch service and repair information
In the meantime, note that Apple advises that you should not continue using a damaged Apple Watch.