To resolve the "Titanic Index Of Last Modified" error, try the following solutions:
→ Never kill an encoding process mid-way. Use -movflags +faststart proactively.
untrunc -f reference_working.mp4 corrupted_titanic.mp4
ffmpeg -i corrupt.wma -c copy -f wma fixed.wma
If you are searching for index of mp4 or avi files, you are likely looking for open directories. However, the "fix" part of your query suggests that something went wrong during download, encoding, or storage.