Press command + option + esc (you can also click the Apple and choose Force Quit from the dropdown menu)
Select the program you want to quit
Click Force Quit
Press control + alt + delete
Start the Task Manager
Select and close the program
MS Office applications generally save emergency copies of users' files. Once the application is re-opened, the user should have the option to use the emergency copy.
If the user is nervous about force quitting an application and losing work, recommend taking a screen shot first (command+shift+4).
Do a hard restart:
hold the power button down for 5 seconds (until the screen goes black and mechanical activity ceases)
restart the computer