This solution worked for me:, pretty much what Oldturkey said. Computer Management, Disk Management, Right click the (Healthy) Primary Partition - of the size of hdd without drive letter, Select "Change drive letter and paths..." Add... I had a Toshiba hdd from a friend that wouldn't even initialize so couldn't add a drive letter, I ended up very pleasingly pulling it apart and smashing it to bits before throwing it in the trash, very disappointed it didn't have the massive magnet in it that the old hard drives used to have. (Bought the friend a new hdd double the size to compensate - was told there was nothing on it anyway)