Recover a lost Photoshop shortcut (resizing brush size)

[Hoogle]

Yes I did
well the things I would suggest is A) check your ALT key is working maybe try the other alt key at other side of space bar seems strange but some keys do fail.
option 2 I know you have reset your preference file but how about going to edit > preferences > general hold down the alt key and the cancel button should change to reset

Also check that under edit > preferences cursor that you have not changed the colour to white in the preview or whatever your background colour is if that makes sense.

Failing all those steps I would agree with a clean install because if that is faulty then I am sure there are other errors.

[purebloke]

Don't know if this was the issue here, but I ran into this issue on Windows and found that some of my shorcut keys were not working because I was in Chinese typing mode. I sometimes type Asian characters and you can toggle Languages that you have installed in Windows by pushing shift+alt. Once I realized and switched out, all was good again. Just thought I'd share.

[zClotaire]

Hello !
I have found a solution to this problem !
In fact, this option work only if Photoshop is laucnh with admitrator right ! So when i simply laucnh Photoshop the resizing brush size using mouse don't work.
I someone have the same problem...