InDesign does not change your font library. Did you make some changes on your computer or a new computer?
When you say that the font is no longer there, do you mean that the font file itself is no longer on your system or that the font is on your system, installed, and that InDesign is simply not recognizing it?
InDesign never uninstalls fonts nor does any Adobe installer or uninstaller ever remove fonts. If in fact the font file is no longer on your system, your best bet is to restore the file from your most recent system backup.