When you click on something and nothing seems to happen, the worst thing you can do is click again.
If it did not respond the first time, doing it a second time will seldom produce a different result. Usually, your computer is busy and just has not responded yet. Clicking again will sometimes begin a cascade of problems. But now, it looks like your computer has frozen.
What to do? First thing you need to do is look down at the Task Bar. You may find something there that is blinking. That would represent a window or dialog box, that you cannot see (because it is behind the one you are looking at) and it is demanding a response. If you see that, click that flashing icon on the task bar and up will pop that window. Respond to it, and then you will have “control” back.
The Task Bar is the area on the bottom of your screen that is between your start button and quick launch icons, on the left, and the clock and other icons in the system tray on the right. Right-click (opposite of your normal mouse button), choose Show Task Manager
The Task Manager has several tabs across the top. Choose the Applications tab. There you should find a list of the windows you have open right now. One of them may say “not responding”. Select that one, and then click the End Task button at the bottom of the window.
You may have to wait a couple of minutes, but it should end that task and give you back control.
If you do not see the task bar, hold down the Ctrl and the Alt keys, then while still holding them down, press the Del key. In Windows 7, it will bring up a list, one of which is Task Manager. That will bring up the Task Manager window.
If all else fails, last ditch, hold the ON button on your computer in for about 5 seconds or more until the computer shuts down. Now restart. Hopefully, your computer will start normally. This problematic behaviour does not necessarily mean something is wrong with your computer. It probably means there is a software problem or a misbehaving web site. If this reoccurs, you need to pay particular attention to exactly what you were doing at the time this occurs.