Damn, i don't know what you can do. Maybe going back to an earlier restore point? Or just spend an hour or two at deviantart.com and other places...that would probably be best if you can't get them back.
I put my brushes in a totally seperate file not even in the photoshop directory. If I need a brush, all I do is replace the brushes with the ones I want.
hmmmm thats a good idea actully. as for me thats never happend but it might do... thats for the tip bruv