Missing included fonts in High Sierra

Someone removed many of the OS supplied fonts. If you don't have a backup to copy them from, you can get them back in a few ways. From easiest (least time consuming) to obnoxious.

1. Copy them from any Mac running the same version of macOS.

2. Restore them from Time Machine, or other backup type.

3. Use Pacifist to extract them from the full OS installer. You can get that by opening the App Store and downloading High Sierra again. If that Mac came with High Sierra, I don't think it will allow you to retrieve the general release version.

4. Reinstall the OS.

If font is removed how to put back in the font book .

1. Close all apps. Form a folder on an empty desktop by pressing keys shift , command , N on the keyboard or can do it in another way right click on empty desktop click on new folder .
2. Click on Go , then Go to folder and type ~/Library open folder fonts ( removed ) , select fonts ( use keys on the keyboard command and A ) , copy it ( command and C)
3. Open the new folder on desktop , press ( command and V ) , removed fonts will be copied into this folder .
4. Open font book via spotlight on top menu bar , click on add fonts or you can do in a different way , open font book & click on plus sign .
5. Deleted fonts will be transferred to its original place .

Look in the /Library/Fonts/ folder. Verify if these Arial fonts are actually there:

Arial Black.ttf

Arial Bold Italic.ttf

Arial Bold.ttf

Arial Italic.ttf

Arial Narrow Bold Italic.ttf

Arial Narrow Bold.ttf

Arial Narrow Italic.ttf

Arial Narrow.ttf

Arial Rounded Bold.ttf

Arial.ttf

See these articles https://support.apple.com/en-in/guide/font-book/restore-fonts-that-came-with-you r-mac-fb34862/mac

Install and validate fonts on your Mac in Font Book - Apple Support

You’re welcome. 🙂