Hello aiza163,
Thank you for reaching out to Apple Support Communities, and we'll be happy to help in any way we can. We understand you're having issues with restarting your watch. Follow the steps listed here to see if you can force restart it and resolve the issue: Restart your Apple Watch - Apple Support
"Force restart your Apple Watch
You should force restart your Apple Watch as a last resort and only if it's not responding.
Don’t force restart your Apple Watch if you're updating watchOS. After you see the Apple logo and progress wheel, leave your watch alone and on its charger until the update finishes.
To force restart your Apple Watch, press and hold both the side button and Digital Crown for at least 10 seconds, then release both buttons when you see the Apple logo."
We hope this helps.
Cheers!