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It sounds like you have a laptop and have got a function key stuck.

_{Keycaps from my Dell 7447}

As you'll see, the FN key combined with arrow keys, at least on my laptop, act as Home, Page up, Page down and End. F11 and F12 control brightness.

Try using the arrow keys with FN held down, and see if their behaviour changes. If so, you may have a Function Lock key, which, on my example, would be FN + Esc (The little padlock with FN in the middle), or Esc alone with FN Lock already on. Without knowing your model it's hard to say for sure, but it is likely labelled on one of the keys, probably in the F1-F12 keys at the top.

You have one of your CTRL keys stuck.

Try to pull them up with your finger nails.

If you are using windows see if StickyKeys isn't activated. Try in Control Panel.