Computer Screen Rotated 90° All By Itself - How Do I Get It Back To Normal?

[AndiFlatland]

As the title says, my computer has suddenly decided to turn the screen through 90° anticlockwise, for no reason to do with anything I did, that I'm aware of. In less than ideal circumstances (the mouse pointer is going in a different direction to where I'm dragging it, which is blooming awkward), I've tried everything I can think of, but nothing works. All I can think of is that shortly before this happened, I was trying to find a way to make the screen a bit brighter, by using the 3 small buttons on the bottom right of the screen, labelled '-', '→' and '+' - but pressing any of them just puts a large padlock symbol on the screen. Any ideas, anybody?
I'm using a Windows 7 ex-internet café computer on Mozilla Firefox.
Thanks for any help.

[Old_Geezer]

Hold down Ctrl and Alt and press one of the four arrow keys

[1ozzy]

Press and hold the Ctrl and Alt keys while you press the Up arrow. Pressing these keys at the same time should rotate the screen back to the default setting.

[AndiFlatland]

Ah, thanks, all of you! I never learned that simple genius trick when I first started using computers - have to remember it.
Now can any of you advise on the other problem I mentioned, about how to make the screen brighter? I'm sure I've done that before, by using the 3 buttons on the bottom right of the screen - but with them all bringing up the padlock symbol, it seems they're blocked.

[Jackdaw33]

A favourite prank at work. If someone went on a break and forgot to lock their computer some wag would rotate the screen. Easily fixed if you know how, as explained above.

[Old_Geezer]

Turn the knob on the monitor in a clockwise direction.

[Old_Geezer]

Function and F5 might help.

[KARL]

If you can access system settings then you should find the screen controller allowing you to dim or brighten the display. I am unfamiliar with Windows as I use Ubuntu but the principle should be similar/identical.

[Jackdaw33]

If it's a laptop you can go into settings and adjust the brightness from there.

[Guilbert53]

Note you can stop your screen EVER being able to rotate.

This is how I do it on my computer (Windows 7 with Intel graphics.) but it may vary on other PCs

Open the Windows Control Panel

Change the "view by" (top right) to Large icons

Click on the "Inter Graphics" option and choose Advanced mode

Then choose Options and Support

You see an option Hot Key Functionality (these are the various keys you press to rotate the screen)

REMOVE the tick next to Hot Key Functionality and press Apply then OK to save your settings.

I future no matter what keys you press the screen will never rotate.