The file or directory is corrupted and unreadable

Thanks a lot for your timely help ;)

thanks a tonnn

thanks it works great

but my important file delete

what version of Windows do you have?

windows 7 64 bit

To run an elevated command prompt under Windows Vista, Windows 7 and the Windows Server 2008 and later family of operating systems:

Click Start
In the search box type in command
Right-click 'Command Prompt' in the search results list
Click 'Run as administrator' from the popup menu
If you are not an administrator of the computer a dialog box will be shown prompting for the administrator password

Windows 8
(Also works with Windows Vista, 7 and Servers 2008 and later if you start at step a.)
To run an elevated command prompt in Windows 8 start at step a. (but if showing START screen in Windows 8 start at step b.):
(see also sample screenshots below for Windows 8)

Press keyboard `Windows key'
Type word 'command'
Then right-click on `Command Prompt'
From menu click 'Run as administrator' (menu is at bottom of screen in Windows 8)
If you are not an administrator of the computer a dialog box will be shown prompting for the administrator password

and now ?

then run your chkdsk command.

But, you external disk is probably broken and your files are lost.