This article will be an evolving article. There are many things that could contribute to a computer crashing (and some of these things don't just apply to Windows).

If your screen has not turned blue with a message saying Windows has crashed....

Try the Three Finger Salute - the first thing to check on an unresponsive computer is that it isn't just the program or application you are using has crashed. Whilst holding down CTRL and ALT keys press DEL (Del is usually found somewhere on the far right of the keyboard). With later versons of windows the screen will show a list of options including Task Manager - you can use task manager to end an unresponsive program.

If neither the keyboard or mouse are responsive, you may simply have to resort to a hard reset - press and hold the power button until the computer switches off, wait a few seconds and turn back on. Whilst you're at it, check how hot the machine has become, if it feels fairly hot to touch it could indicate and ingress of dirt and fluff has accumulated around the cooling mechanism (particularly in laptops) - make sure that air flow is not restricted, you can try blowing into the fan inlets to loosen any debris which hopefully when you turn back on will get blown out (this is not a permanent fix, you should seek to have your machine disassembled and cleaned).

You can monitor CPU temperature with a free utility from here: this utility can be set to run on system startup in the system tray and alert you if it gets too hot - you will need to adjust settings to determine what the machine should do if it does get too hot such as shutdown or just alert you.

Check power settings on your computer - in windows 10 search for  'Power Plan' and go to edit the power plan - then change advanced power settings...

If you are set to high performance, your CPU will be working harder for you and in doing so will get hot. Try the balanced power plan or power saver power plan.