If a font you just installed doesn't appear in Word, Photoshop or another app, it's usually one of a few causes: the app was already running before you installed it, the font is installed only for your user account, the file has the wrong format, or the same font is installed twice. Work through the steps below in order; the most likely fix comes first.
Many apps read the font list only at startup. Close the app completely and open it again.
Make sure the font really is installed: on Windows under Settings → Personalization → Fonts, on a Mac in Font Book.
On Windows, uninstall the font and reinstall it with right-click → "Install for all users". That helps with older apps and with apps running with administrator rights.
Desktop apps need TTF, OTF or TTC files. WOFF and WOFF2 files are web fonts and can't be installed.
If the same font is installed in several versions, or as both OTF and TTF, apps sometimes show the wrong one or none at all. Keep only one version installed.
If nothing else helps, restart your computer so every app and system service loads the font list fresh.
If Windows shows an installed font wrong or not at all even though everything else checks out, the font cache may be corrupted. To reset it (this needs administrator rights):
Font Book can check fonts for problems and flags fonts that are installed twice with a warning. Select the font and validate it from the "File" menu. You can deactivate or remove damaged or duplicate fonts right there.
The free typest.app font manager installs TTF, OTF and TTC files straight from ZIPs and, on Windows, registers new fonts with the system right away. "Installed" lists every font on your computer, so you can see at a glance whether a font really is installed and remove the ones you no longer need in one click.
Restart Word. If that doesn't help, install the font for all users and check that it's a TTF or OTF file. Word sometimes handles variable fonts only partly; use the static files then.
Restart Photoshop and check whether a filter is active in the font menu. Search for the font's family name; it can differ from the file name.
No. WOFF and WOFF2 are compressed web fonts for websites. Download the font as TTF or OTF instead; Google Fonts gives you that format automatically.
Usually not. Restarting the app you want to use the font in is enough. Restarting the computer is only the last step when nothing else helps.
