USB keyboad not working

Windows10 USB keyboard does not show keystrokes.
I tested it in notepad. The built in keyboard on the Lenovo laptop still works fine, but not the external keyboard.

I have a PS2 keyboard which works just fine on another computer. Also have a PS2 to USB adapter which is new. When any PS2 keyboard is plugged into the adapter then Windows10 responds with the same sound that it makes when a flash drive is plugged into the USB port. So I think there is not a hardware problem with the keyboard or adapter. However the keystrokes from the external keyboard are not recognized. The lights for capslock and numlock don't come on when those keys are pushed. Device Manager says the keyboard driver is okay. Scanning for new devices does not help. "Settings" does not have a selectable category for keyboard. Rebooting the laptop with the external keyboard does not help.

Does anyone have a suggestion how to get a laptop to work with an external USB keyboard?

The PS2 to USB adapter you are using is probably passive. You need to get a "active" USB to PS2 adapter. Just do a Google or eBay search for one. Make sure to include the word active.