If you want to bring back the original settings of a command keys, you may change the keyboard keystrokes to the default settings by doing the following step below:
1. Go to the Tools menu and select Customize
2. In the Customize dialog box click, the Keyboard button
3. The Customize Keyboard dialog box will appear
4. Click Reset All…
5. Click Yes in the pop up box
6. Then click Close
7. Click Close on the Customize dialog box