My computer froze, how can I fix it?

Sometimes, errors occur that cause the computer to stop working. The computer automatically pauses the program or programs inflicted with the error until it can be corrected. In many cases, this conflict can be corrected by forcibly ending the program by simultaneously pressing the Ctrl, Alt and Delete keys until a window appears.

The window has a list of programs on it. If a program has the tag line [Not Responding], select the program and press the End Task button on the window. 

If the problem keeps persisting, then it means your computer's hard drive is going out. If your computer has been slowing down lately then it's time to replace it.