There’s a file called SettingsLocations.ini that you can edit with notepad which should fix the problem.
For me, this file is located at in C:\Users\Admin\AppData\Roaming\Dell\Toad for Oracle.
Find the entry in that file for 12.10 (there could be multiple Toad versions listed in there)
For me, it looks like this:
[TOAD 12.10]
AppData=C:\Users\Admin\AppData\Roaming\Dell\Toad for Oracle\12.10
Path=C:\Work\Installed Toads\Toad for Oracle 12.10
Version=12.10.0.30
Edition=Toad DBA Suite for Oracle - Exadata Edition
Then you can change the AppData path to whatever it needs to be. Save and close. Next time you start Toad, it will create the folder if needed and create the user files folder within.
That worked in a quick test for me, but if it doesn’t work for you, then a reinstall should take care of it.