How to retrieve video that show unknown error

[AC Question]

When I tried to reduce video length something happened and the only picture that comes up is a grey screen with icon with exclamation point.

 

[B. Diddy]

Welcome to Android Central! How were you trying to edit the video? Did you back it up at all? If not, and if the file got corrupted from what you were doing, then you're probably out of luck.