my apple watch can't update to the new version

Hello shanti115,

To help us better assist you, can you let us know more about the issue? Is your Apple Watch not powering on at all now?

If your Apple Watch isn't powering on, the link you came from has some information that can help with that issue: If your Apple Watch won't charge or it won't turn on

If your Apple Watch is now powered on, but it's unable to update, please check out the details from the "If you need help updating" part of this link, which explains what to do if you have trouble updating: Update your Apple Watch

If you need help updating

Try these steps:

1. Make sure that your Apple Watch connects to its charger. 

2. Restart your Apple Watch. Press and hold the side button until you see Power Off, then drag the slider. To turn your watch on again, press and hold the side button.

3. Restart your paired iPhone.

4. Try to start the update again. 

If the update won't start, open the Watch app on your iPhone, tap General > Usage > Software Update, then delete the update file. After you delete the file, try to download and install watchOS again.

Learn what to do if you see 'Cannot Install Update' when updating Apple Watch.

Thanks!

Also see:

apple watch 3 series won't update , watch… - Apple Community

https://www.upphone.com/fix/devices/apple-watch/my-apple-watch-series-3-wont-update-heres-the-fix/