Almost all interactions between a user and his computer run through a mouse or keyboard, so it is incredibly problematic when they don't work in Windows 10.
Most often, when a keyboard or mouse is not working, it happens after a Windows update or biannual feature upgrade and indicates a problem with the device drivers of the mouse or keyboard itself.
Because a mouse or keyboard usually attaches to a Windows PC via the USB, however, the issue could be with the USB or one of the intermediate USB hubs between the device and the PC's motherboard. This applies to Bluetooth or radio frequency devices, as well, simply because the USB usually acts as the intermediary between the mouse and keyboard and the motherboard.
When the keyboard or mouse is not working, users lose their main tools to input directions into a computer. Fortunately, there are some fixes that you can try as an IT professional to solve this problem.
Check the hardware
It's not a cure-all, but restarting Windows 10 is a shortcut when the keyboard or mouse is not working. With any luck, the computer will detect a missing or mangled device driver during the device enumeration phase at startup. By the time the OS is running and ready for login, the computer will have taken care of the issue on its own. You can also boot the faulty PC's basic input output systems (BIOS) to determine if the Windows 10 keyboard or mouse is working properly in the BIOS or unified extensible firmware interface.
Often, if you try a different mouse or keyboard with the user's device and it works, a worn-out battery is to blame. If the battery is still working and a substitute device does work, you should focus on fixing the original device or find it a working driver.
If you are lucky enough to have a touchscreen PC when the external keyboard or mouse is not working, you have an internal alternative to troubleshoot the hardware. If the touchscreen works, you know the problem is somewhere in the device chain from the mouse or keyboard to the PC. The break in the chain could be the USB port, a USB hub, a wireless connection or the device itself.
Troubleshoot the different possibilities to figure out what's causing problems with the Windows 10 mouse or keyboard. You should try a different USB port, and if that doesn't work, try a different hub.
Windows image repair and remote connections
You can create Windows recovery media to gain access to a bootable Windows image. If you boot into the recovery disk and the mouse and keyboard are working, something is wrong with the primary Windows installation. You can back up the drivers from their recovery image at the command line using the Deployment Image Servicing and Management (DISM) tool, and you can use that same tool to install the same drivers on the wounded Windows image.
Troubleshooting hardware problems with image repair, however, is sometimes more work than it's worth. Some PCs support remote desktop connections, which you can use for repair but require Windows 10 Pro, Enterprise or Education.
You can access the problem desktop with Remote Desktop Connection Manager. Then, you can attempt driver repair or replacement from a different machine. In this case, you should try either Device Manager or use DISM to work on the device drivers for the mouse or keyboard.
Unfortunately, these repair steps do not solve all the issues when a keyboard or mouse is not working. If you are troubleshooting hardware with these steps and it doesn't solve the problem, it's time to call in somebody with professional-grade PC troubleshooting and repair skills.