It could be one of several problems:
1. Your preferences need a reset
2. A font you have installed might be corrupt
3. You may need to uninstall and reinstall PP
If you have any other Adobe application e.g. After Effects, PS, ID etc you can try to change fonts and see what happens.
If its fine then I would recommend an uninstall of PP and a fresh install
Let us know how it goes
Mo
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