Now that you’ve resolved the cause, prevent recurrence:
Uninstall any "faded" or grayed-out keyboard entries before plugging your keyboard back in. Super User Driver Details for Reference Casue Usb Keyboard Driver Windows 7
can sometimes provide broader compatibility for non-Microsoft hardware on Windows 7. Are you seeing a specific error code (like Code 10 or 43) in Device Manager for the keyboard? Now that you’ve resolved the cause, prevent recurrence:
Casue Usb Keyboard Driver Windows 7, USB keyboard driver failure, Windows 7 HID driver, fix USB keyboard not working, kbdhid.sys error, USB selective suspend Windows 7. Now that you’ve resolved the cause
If none of the above fixes work, the cause may be deeper: