How can I access something like Task Manager in Windows to kill processes that are hogging memory? [duplicate]
Hit CTRL+ALT+F1 and you will get into a login terminal.
Enter your login details.
Enter sudo ps -A - this lists all processes running on the computer.
Write down the process ID - PID of the stuck process.
Enter sudo kill PID where PID is the process ID of your stuck process.
Hit CTRL+ALT+F7 to resume the graphic mode.
In case the graphic mode is stuck enter in the CTRL+ALT+F1 screen sudo service lightdm restart.