delete / backspace Arrow keys. all suddenly switch.

I have Imac with small wireless keyboard. (no back space key or number pad).

Forever my delete key acted like back space erasing to the left behind the curser.

Now suddenly it is erasing to the right in front.

Also my arrow keys have turned into page up page down keys. Which makes the back space issue more difficult as I cant easily erase quick mistakes. I have to use my mouse to put the curser at the front of the error and hit delete.

It was "normal" for years. Now its driving me nuts. On two occasions I restarted the computer and it reverted to the way it had always been, i was thrilled. But it didnt last long.... upon next restart its backwards again.

I cant find any info on this anywhere. Why did it switch? Why did it switch back? Its driving me crazy.