How to fix backspace?

Question

Windows

Filled the keyboard, and while wiping it pressed a bunch of keys. Now backspace works weird.
For example:

123
456
789

If you move the carriage to the second line (456), and press backspace, then after deleting the number 6, the caret will jump to the beginning of the third line and will not continue to delete the second line.

Or if you
12345678
move the caret to the number 5 in the line, for example, and start pressing backspace, then the caret will remain in one place, and it will delete the text inexplicably.

How to fix it?

Answer 1

Buy a new keyboard.
Nothing will help, the time and nerves spent are more expensive.