If your Apple Watch freezes or suffers some other major issue, you might need to do a forced restart. Note: only force restart any device if more "tidy" options have failed; also, do not do this during a software update unless it is absolutely necessary.
Here's how to do the restart...
Hold down both the side button and the digital crown. Hold them down for at least 10 seconds. Release them when you see the Apple logo. The watch should now restart and hopefully the problem will be gone.
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