回复：Have you tried ? - Asked for initialize Disk

Don't initialize!!! Not now.

From your previous post, I thought only the drive letter was lost. The procedure I gave earlier allows to assign a drive letter to your Portable HD.

Now that it requires to initialize disk, this means the P. HD was damaged somehow and its format is not recognized. Your best bet is to find some recovery software which can get your data back.
Reinitialize the HD only when there is no way to get the data back!

Do you remember what you did to the machine before the problem occurred?

Another advice is : dont connect your P. HD to your PC all the time, particularly when you install software. Connect only when you need it, which would reduce the chance to damage your P. HD.