I am unable to copy data from my external hard-disk (NTFS). When I try to repair it from cmd using chkdsk I am getting above subjected error. Please advise/suggest how to get through this issue.

I understand that you are getting an error “Snapshot was deleted. A snapshot error occured while scanning this drive. CHKDSK cannot continue.” While trying to scan a Hard disk which you cannot copy files from.

For better understanding of the issue, please get back to us with the following information:

What is the make and model of the external hard drive? Does the issue occurs while performing check disk on a different drive?

I suggest you to Disable Snapshot Schedule and then try performing check disk.

Follow the steps below to do so:

Deleting a Snapshot Schedule

https://technet.microsoft.com/en-us/library/gg232616%28v=ws.10%29.aspx?f=255&MSPPError=-2147217396

If you are still facing issues with it, please start the computer in safe mode and check if the issue persists.

Follow the steps below to start the computer in safe mode:

http://windows.microsoft.com/en-us/windows-8/windows-startup-settings-safe-mode