Hard drive hidden in disk/device manager

Hi. I tryed to make a system back up but it keeps failing with error code0x80070002) (windows cant find a backup device) went into disk manager and found that my external hard drive that I had plugged in to make the backup on was present and working fine, the strange thing was that i couldnt see my internal hard drive, I did the command promt "devmgr_show_nonpresent_devices=1" this enabled me to see the disk in device maneger but windows was telling me that the disk was not connected to the system? system restore wont work and like a fool i deleated my previous backup image to make room for the new one. I also tryed startup repair and this failed to find any errors, I should point out though that windows explorer shows my internal hard drive, which is the drive my OS is running from but disk manager refuses to show it and i dont get a "show hidden devices" in the view tab either. I also have XP installed on a different partition to run some old stuff i like to use and the disk manager in xp is also hiding my hard drive. any ideas??