all presets gone after changing version

I have downgraded since Hue/saturation adjustment does not update in real time on my computer in v 21.1 (windows 10)

There's a saying that is too appropriate in this situation...'it's not a bug, it's a feature.' UGH. I have not upgraded to the latest and I AM on win 10 (speaking of buggy). When you say it doesn't update in real time...what happens?

you have to release the slider indicator in order to see changes in Hue. On previous versions, color updated in real time, while you were scrubbing.

Interesting...I don't often, if ever, change hue but I change intensity of color all the time. Thanks. I'm on 21.0.2 and think I will leave it there until this is fixed. Thanks.

Rather than using your mouse cursor to scroll sideways, you should instead use the middle mouse button on the numerical value of the hue and scroll up and down. It works exactly the same as if it was in real-time.

Nice solution. Now if we could only find out why all the presets disappeared. I don't know if I could even recover them if that happened to me. I have actions that date way, way back and don't think I even know where I could find them on my computer (if they even exist...somewhere) to reinstall. Win 10 as a whole has not been a happy experience for me.

You should regularly back up everything on you computer. If you have, you should be able to find your old presets.

What I don't know is how to back up my presets and actions and if I do, where it should be saved. Again, I'm on Windows 10 desktop computer. I think that is a very wise thing to do. Interestingly, back in 'olden times,' there was a question about whether one wanted to save presets, etc. For a while, the default was no. Apparently enough people screamed so then the default was changed to yes. And then, somewhere along the way, the choice disappeared completely. I've been using Photoshop since nearly the lst version so I can't tell  you how far back that was but it was before the subscription versions, I think.

Yes, I agree.  I regularly backup my presets ( this time though, I didn't for about two months, so goodbye to all the specialized brushes). 
The preferences are gone as well, so all these need to be set again, and that can be an annoyance.

Omar, how do you back up the presets, etc. What is the procedure on a Windows 10 computer? And wouldn't you have previous backups you could install?

Yvette, I haven't used presets in Ps for quite a while. I mostly use them in Lr. However, I just had a look in Ps. On my PC (Win10) my presets are stored in the default folder: C:\Users\marsha\AppData\Roaming\Adobe\Adobe Photoshop 2020\Presets. In Ps there is a preset manager: Edit>Presets>Preset Manager (also Migrate Presets & Export/Import Presets). I hope this is of some use.

One thing you can do is save actions, swatches and brushes from their respective palettes. Just click on the tiny menu at the top right corner and click the right menu item to save. From there you will also be able to load them should something go wrong in the future.
As for the rest of the presents, they all hide in some folder on your computer. You can just copy it somewhere in case. it's here ( X marks the PS version)
C:\Users\[User Name]\AppData\Roaming\Adobe\Adobe Photoshop CC X\Adobe Photoshop CC X Settings

Thanks so much, both of you. Meanwhile, Marsha...totally unconnected to this...I've never been able to use Lightroom because I can't read white letters on a black background (it's a quirky problem of my eyesight). Plus the history states are backwards from Photoshop. And since virtually everything I want from the program is duplicated in Photoshop (mainly the tools in Camera Raw) I just stick with PS. I truly would like to wring the neck of the 20-something developer that thought white text on a black background is cool and didn't provide a way in LR to change this. 

Yvette. What a nuisance. I really like Lr. It never occurred to me that the text and background couldn't be changed. If it can't be, that would be a good request to make.

Some  years ago I attended a workshop that spent the better part of a day leading people through PS and LR. (One of those sessions that costs $99). At one of the breaks, I grabbed the LR tech guy and asked about this and he said, no, it couldn't be changed.  He seemed stunned that I even asked. Oddly, the background shades CAN be changed in PS. I explained my unique problem and, of course, that went nowhere.  I tried using LR for a while and finally gave up. I have my own catalog system and beyond that, there are few things I want in LR that PS doesn't duplicate.