I had spent almost entire day to find and fix the easiest solution to this problem.
Why this error appears?- If you remove your hard disk or pen drive while it is in use by your Computer/TV/DVD Player. So always unplug it through "safely remove device" or if your pen drive or Hard disk is plugged in your TV or DVD player then first switch off your TV/DVD Player and then remove it.
Now how to fix this error? So here we go-
Download "testdisk" and run testdisk_win.exe.
Select CREATE and hit enter.
Make sure your external disk is highlighted. Select Proceed and hit enter.
Select Intel and hit ENTER
Select Analyse and hit ENTER
Select Quick Search and hit ENTER and wait for few seconds
Press P to see your list of files
now your files will be available here (if still you are not able to see your files then select deepar Search
now you can see All your files. Press C or c to copy the files. (mind the Caps lock)
Now select the destination where you want to save all your files.
After saving all your data. now you format the hard disk and copy all your data from the destination where you have saved your files.
Contact me if you are facing any problem.