It's worth checking the previous version presets folder, which might still have your presets.
The beta version has a different presets folder to the release version, so if you have that installed, they might be there.
I personally keep my brush presets in a My Docs folder, and place a shortcut to them in the Photoshop presets folder. This safeguards them against catastrophes, and means that when I add a new ,abr file, it is available in all versiions. There is obviously some housework to tidy up if making new presets inside Photoshop.
... View more