The reason "PasteUnformatted" does not appear on the list is because it's not a Word command. My guess is that you created a command with that name, but it's been lost. You would need to use VBA, Word's macro language, to recreate it.

But I think you may be able to create the same functionality by following these steps. To set this up, you'll need a keyboard that has a numeric keypad: the first step requires the use of the plus-sign on the keypad. During the process, you'll assign a hotkey to activate the command. Your chosen hotkey doesn't require the keypad.

Start by copying some formatted text to the clipboard.

1. Press Ctrl + Alt + Plus (on the numeric keypad).
2. The mouse pointer will change into a cloverleaf.
3. Click the Home ribbon.
4. Click the little downward facing arrow under the word "Paste"
5. Four paste options will appear. The one you want is probably the rightmost. Hover the mouse cursor over each option. Click the one that says "Keep Text Only."
6. A dialog box will appear that will allow you to assign the command to a hotkey. Assign the hotkey, and close the dialog box. You're done. Test your hotkey.

If the above doesn't work, and you're not up to recreating the macro, this sequence of four key presses should achieve the same thing, with zero mouse clicks. Press the first key and release it. Press the second key and release it, etc.

Start by copying some formatted text to the clipboard. Then press the four key sequence. No need hold down two keys simultaneously. In fact, the key sequence will fail if you do so! Press the keys one after another, and hopefully you'll be fine.

Alt
H
V
T

or

F10
H
V
T