Sometimes one can get a little to experimental and Photoshop becomes impossible to control. To restore the preferences to default factory settings follow the steps bellow: 

How to reset Photoshop (In Windows):

1. First, hold down all three Ctr+Alt+Shift buttons
2. Now while keeping those button held, simply open Photoshop or a file that opens with Photoshop
3. As Photoshop loads, you should get a prompt asking if you would like to “delete the Photoshop settings file”, Click yes

You should now have a fresh slate with all of the settings returned to their default.