I'm not sure how that would help??
I'm sorry that you ran into trouble with this! If I understand right, you had a bunch of fonts installed on your Mac (in Font Book), and some of them aren't showing up anymore.
> "although when I'm opening a file suffix .idml they appear to be available"
If you make a new InDesign document, can you select the fonts from the type menu? Or they only seem to be available when you re-open a document that uses them?
Do you remember the names of one or two of the missing fonts?
Could you post a screenshot of the type menu in InDesign and one of Font Book, so we can get an idea of what you're seeing in both places? Here are instructions on how to do a screenshot on OS X, in case you need them: How to take a screenshot on your Mac - Apple Support
Thanks for your help,