You'll probably need to rest items in a couple of areas, but I hope this helps:
Keyboard Shortcuts: Edit > Keyboard Shortcuts (There is a dropdown for default)
Menu: Edit > Menus (There is a dropdown for default)
Preferences: Preferences > General > Reset All Warning Dialogs
This should get you started.
you can reset the Photoshop preferences in the following way
Windows: Shift + Ctrl + Alt
Mac: Shift + Command + Option
Hold down the above keyboard combinations while starting photoshop.
You will be asked if you want to reset preferences -answer yes.