If you have a problem with the Lenovo wireless keyboard and mouse set, where the mouse works fine, but the keyboard doesn’t, then you need to take the batteries out of the keyboard and leave them out for a good few minutes to remove any residual charge. Then put the batteries back in the keyboard and it should work fine. If this doesn’t work, do the same with the mouse and keyboard at the same time and also remove the wireless receiver, then put the receiver back in and the batteries back in and it should work.