My Apple Watch did not record my whole workout

Without knowing any specifics, the first (and simplest) thing to try if something isn’t working right is to restart your Apple Watch and its paired iPhone. If necessary (device not responding), try a forced restart. Both methods can be found here:

How to restart your Apple Watch - Apple Support

Restart your iPhone - Apple Support

The next steps would be to unpair and pair your watch again and restore from the backup:

Unpair and erase your Apple Watch - Apple Support

Set up your Apple Watch - Apple Support

Try this;