Not sure if it will help you in current situation, but always render frames so that you have a backup or at least can see in the frames what went wrong. Most people in the forums here don't even render the video output, they will do the frame output only, and will then import the frame stacks to Premiere or AE or whatever video production program they favor. It also saves some production time as Keyshot isn't converting video between renders.
Now, if you did happen to check the box for frame output, then you should have a folder sitting somewhere with all of the rendered frames in it that you can use if the converting idea doesn't work out for you.