|Are they wireless and do they use USB's?|
Did the mouse and keyboard come together using common software? If so maybe that needs re-installing - uninstall from Safe Mode if necessary.
Tap F8 while booting and select Safe Mode. It will eventually produce a screen with large icons and the words "safe mode" at each corner. See if the mouse and keyboard work then because they will then have minimal drivers. Have a look in Device Manager to see if there are any colored error marks showing.
We all live on a ball.