If you ever need to reset Photoshop to its factory settings. To do so, you need to delete the Adobe Photoshop Settings File by pressing Ctrl Alt Shift (Mac: Command Option Shift) immediately after you click to start Photoshop (and I mean immediately after, not a second later. If the program starts you took too long to press the keys).
Then click “Yes” in the Delete Settings File dialog box. Without a settings file available, Photoshop will use the factory-set defaults. Remember that you CANNOT undo this action.
For more tips and tutorials, subscribe to Photoshop Training Channel on YouTube!