Hi
Lack of relevant information so just some guesses
Did you use an old windows hard disk in a new PC ?
Are your keyboard & mouse USB ? If so is there a ps/2 port and ps/2 keyboard available
Is this even a Windows PC ? Or Linux ?
Is the old motherboard still working and available ?
Consider booting up from a USB or cd live Linux disk
See if keyboard & mouse are working
( if so continue if not maybe a hardware fault which needs fixing)
Were you connecting to USB 3.0 ports which may not work until drivers loaded ?
Rescue any data to an external drive
Re install your operating system
Regards
Mike Barnes