Q: Magic mouse suddenly stopped scrolling

Hello GBASHAW,

After reviewing your post, it sounds like the touch features on the Magic Mouse work, but you are not able to scroll. Are you having trouble scrolling in Safari or in other applications? You may want to check if scrolling has been disabled for a Trackpad or Mouse. 

Use Multi-Touch gestures on your Mac - Apple Support

In this case you would select Mouse Options:

Trackpad scrolling can be turned off in Accessibility preferences: Choose Apple menu > System Preferences, then click Accessibility. In the Mouse & Trackpad section, click Trackpad Options, then deselect the Scrolling checkbox.

Thank you for using Apple Support Communities. Have a nice day.