How do I stop this intermittent typing crazines?

This may be a very dumb and basic question, but I need to ask before I go berserk.

I have a PC. Somehow, I hit a key ( ?) which now makes me type backwards, with the cursor going in front of the last letter I typed.

I can’t seem to get out of it, even if I turn off the computer.

Please help me before I go insane?

(I’m sure this is an easy answer)

Tankyou, n adane.cvi h