I need help to unblock my Apple Watch

Unblock it how? When you post here you need to give a very detailed description of the issue so folks here can offer ideas or solutions.

Is your watch locked because you entered the passcode incorrectly too many times? This link provides a solution for that;

https://support.apple.com/guide/watch/if-you-forget-your-passcode-apdbebcd1d3b/watchos

Is your watch blocked by an Activation Lock? That is protection to prevent lost or stolen watched being used by others. Unless you know the original user and they disable activation lock, you can never unblock this watch.

M1 Mac mini, macOS 11.2.2; Watch, series 5 GPS/cellular, watchOS 7.3.1; iPad Pro 2nd Gen, iPadOS 14.4; iPad Air 2, iPadOS 14.4; iPhone 12 Pro, iOS 14.4; TV 4th Gen, tvOS 14.;  HomePods, audioOS 14.4 and Airport Express w/ Airplay 2