Exporore Harddrive not working

On Saturday 20 the was power on and off again and the explorer came back again then it said hard drive full please format hard drive i tried doing it but at last end if said Fail and the decoder will work without PVR settings and now for it to work i need to switch it off and back on AGAIN from saturday till today monday pls help what must i do and it started making nois when its on i can't even change channels...