Why are you getting numbers appearing on screen when you type letters on your computer keyboard? Try pressing a FN key with a Num Lock, a Shift key & Num Lock, CTRL Key & Num Lock, ALT key & NUM Lock. Do k, l, m, and n key have numbers printed on those keys themselves? If you have an IBM Thinkpad there is a key that will turn on numbers lock on, and it may have been pressed by accident.
You may have numlock turned on accidentally. If it's an external keyboard and not laptop keyboard, you can unplug it and plug it back in. If it's a USB external keyboard you can try plugging it into a different USB port.
If you have a laptop press a scroll lock key. Try holding down a FN function key while pressing a scroll lock key. Hopefully, your numlock key is no longer locked.