so i have this toshiba 500 ext HDD and i have just experienced this problem. the ext hdd wont appear on the win explorer but on the device manager and taskbar says that it is working properly. tried to uninstall it but it didn't work. iv'e tried disk management and there is 2 disk, disk 0 which is inside my laptop, and disk 1 my ext hard drive. the difference between the two is the disk says that it is unknown and not initialized. and disk one has no black bar nor blue bar. and whenever i try o initialize it, it says " the disk cannot find the sector requested". please help and sorry for the long post.