Keyboard types numbers instead of letters (Wired keyboard)

The cable that connects the keyboard and your computer must be set properly, i.e. not bent, cut, or under pressure, so that the keyboard can function properly. Position it properly and try checking again if the keyboard types numbers instead of letters, again.

Maybe a key on your keyboard got stuck, resulting in your keyboard typing numbers only. Inspect your keyboard closely, and unstick a key, should you identify a stuck one.

If the device's USB or PS/2 port has accumulated dirt, your computer may not receive the instructions from the keyboard properly. In this case, you will need to clean the ports.

The safest way to clean ports is using a vacuum cleaner, but make sure that you reduce its suction power as much as you can.

Note: Don't use a screwdriver to clean USB ports because you might damage them. For example, you can use a toothpick, instead.