As I had to experience myself, Windows 10 or some versions of Windows 10 do not automatically support old PS2 Keyboards and mouses. I have been researching a bit and found a possible solution.
1) Open the Windows registry editor by searching for regedit:
2) Go to registry path
3) Change registry value:
The value of the entry ‘Start’ must be changed from the default value 3 to 1. It does not matter if the value is decimal or a hex value.
4) Reboot the PC:
After a reboot the PS/2 Device should work on your Windows 8 or Windows 10 pc!