I put this same discussion first in Photoshop General Discussions, but a member pointed me here, as it may be more appropriate?
So, I'm running the latest version on a Mac with 16GB RAM etc. Photoshop 2015.0.1, Yosemite 10.10.5.
I have cleaned up the fonts with Font Book, even removing a couple where they were marked as warnings, and duplicates.
Now, everything else on the system (Word, Pages etc) reads the fonts correctly, except Photoshop, which seems to be seeing mostly every font on the system, but unable to handle some of them. The odd ones seem to be music notation from Sibelius, and some fonts from Microsoft Word and some others I know nothing about. They show up in the Preview list by name, but there are no samples, or the samples are broken, and selecting them has no effect. The Sample part shows up as a little square box - or a blank, or a notation of some sort, or not even the word sample.
I've tried everything, even deleting the caches and so on, and then another user tells me that apparently it;s only in Photoshop that this happens?
These images are some samples of this behaviour. Note the last image has no samples at all, not even broken ones.
Thanks for any advice
Those fonts are not corrupted. They simply have no support for A through z characters (or have other other shapes in their place).
For example, Gurmukhi MT Regular is meant to be used with the Punjabi language, and does not support Western languages such as English.