fonts disappeared

In addition to the other suggestions, empty panels can be caused by corrupt cache files.  See Reset InDesign Preferences and Other Troubleshooting for directions on clearing caches, and for replacing the InDesignSavedData file.

Have you inadvertently applied a filter to the font list?

Mac or PC? What version of operating system? Which version of InDesign? Do you use a font manager program? Where did you get your fonts?

We're willing to try and help, but we need a lot more information from you so we can.

Randy