I've had my iMac for over a year now. I was able to use it fine this morning then put it to sleep, when I returned my iMac wouldn't recognize the mouse or keyboard (wireless). My husband tested all batteries and found they are all like new, but replaced them anyway. I turned the computer off and then on again and still nothing. I can't look at preferences because neither of them (the mouse or keyboard) are recognized to see if anything was changed. Can you offer me any help?