try replacing the battery for both. make sure you are not blocking the receiver - if possible make sure there is a line of sight between the mouse/keyboard and receiver.
I can't tell you how disappointed I am with this computer. On day one I noticed that the option to change screen brightness is not available. So I had to download HP My Display to be able to adjust it. But this is not the biggest problem. After a week the wireless mouse started behaving weirdly. It started to lag and move very slowly. Keyboard was working properly. Than the next day I turn on the computer and the keyboard is not working. The only 3 button that work on it are mute, + sound and - sound. I restored my computer to earlier time and keyboard started working again. After I restarted computer the same problem appeared again. Only 3 buttons on keyboard work. I don't know what the problem is. Maybe someone can help.