BASIC TROUBLESHOOTING
If that didn't work, you have no choice: you have to turn the computer off with the power switch. Wait 10 seconds and then restart the computer.
If the computer starts up, launch the applications you were using when the crash occurred. Some programs, like Microsoft Word, make timed backups of your work and may bring up recovered files. Save these files under different names and compare them to earlier saved files.
If the computer does not start up (contact IT team via ticketing system or other means)