Troubleshoot Font Book problems on Mac
If you have trouble using the Font Book app , see the troubleshooting suggestions below.
If you can’t open Font Book on your Mac
If you try to open a version of the Font Book app that can’t be used on your Mac, an alert message is displayed. If Font Book won’t open, make sure the version of Font Book you’re trying to open is located in the Applications folder. In the Finder 
, click Applications in the sidebar, then double-click Font Book. See If you can’t open an app.
Tip: To open Font Book from Launchpad, click Other, then click Font Book.
If you can’t deactivate or remove a font
Some fonts are installed and activated automatically by macOS. System fonts can’t be deactivated or removed, and the Deactivate and Remove options are dimmed in the menu.
If fonts are missing from Font Book
If no fonts are displayed in Font Book, you may need to restore them. See Restore fonts that came with your Mac using Font Book.
If fonts don’t appear in third-party apps
For help using fonts in third-party apps, such as Microsoft Word, check with the developer. See the Apple Support article Contact a third-party vendor.
If the issue continues after troubleshooting, contact Apple Support.