It sound like your User ID Photoshop Preferences were reset so all you have are Adobe default Brushes in Photoshop. If you have a backup you may be able to restore you user ID Photoshop Preferences. Your brushes would be in a file like on Windows:
"C:\Users\Your User ID\AppData\Roaming\Adobe\Adobe Photoshop CC 2017\Adobe Photoshop CC 2017 Settings/Brushes.psp"
Yeah, I do have a backup, but there isn't anything in that file.
Have you checked the App Data\....\presets folder JJ linked to?
If you just have the default sets, you might be looking at the Program Files folder hierarchy.
C:\Program Files\Adobe\Adobe Photoshop CC 2017\Presets\Brushes
I take it you have also tried right clicking inside the document window with the brush tool selected, and clicking on the little cog icon?
What Photoshop version are you using, and have you had earlier versions installed on that system? If you have had earlier versions look in the presets folders for all earlier versions in both Program files and App Data.
[EDIT] I have just checked, and I have all my brush sets in the CC 2015.5 App Data presets folder.
What brushes do you rely on? They are not so hard to make your own, or collect. I back up the entire App Data tree when reinstalling the operating system, because so much is stored there.
I've tried everything you recommended and none have worked so far. I have a few I rely heavily on (around 20) but I don't remember the name of them or where I got them from, I just used them so much I just know where they were so I didn't really need their names or anything. The folder you show is empty for me.
I'm sorry to labour the point, but have you tried all the locations? I was referring to several places that you might find them. It's just that it is really hard to delete _all_ of your brush sets. Actually, I guess if you had the folder selected and hit delete, that would do it, but only if you have been delving into App Data folders.
Try this. And note we are assuming you are using Windows as you have not bulked at the App Data References.
If Windows 8.1 or 10, make sure you have both Hidden Files and Folders and File Extensions set to be visible. (I'm sure you know this, but lets make absolutely sure we are all on the same page)
Open My Computer click on the System drive (C:\) and in the search window type *.abr
Hopefully this will locate your brushes. If it does, right click one of your favourite brush sets, and chose Open file Location
Try not to do this with one of the default sets.
If you are really stuck and have lost your brushes, I'm guessing you like to paint horses. So come back and we'll try and get David Cole ( davidc1815 ) to join the thread and get you on track with some useful brush sets.
I use Skin & Hair Texture Brushes by Castrochew for >90% of my digital painting with a few modified brushes Like small fully hard round brushes with size jitter set to Fade. These are good for things like eye lashes and flyaway hair. The skin texture brushes in the Castrochew set are really good as well, but need to go on their own layer set to very low opacity. Check out the skin texture on the shoulders on this digital painting of my wife
If you are into painterly type effects, then John Derry's Impasto brushes are excellent. These are are .tpl (tool presets) rather than .abr (brush presets).
John has some excellent titles on Lynda.com Worth a subscription just for those titles, but if you do sign for the trial period, also have a look at Bert Monroy's People tutorials. Not horses, but the techniques are relevant
Sorry for the late reply!
When I search for *.abr, nothing but the default brushes come up.
Thank you for the recommendations, I'll look into them! I am an Equine artist so having the right brushes would help a lot. Thank you for helping so much! I guess starting fresh can be nice sometimes, haha.