- You must already have two files from the broken download. One is the filename and the other with extra .part extension. Move both of these files to other directory (please do not copy).
- Start download again from the beginning, but you have to make sure that it must have exactly the same name.
- Let it download for a few bytes just to have those files created again. Now pause this download.
- Go to the folder where you backed up those old files. Copy both of these files to your download folder and replace the new created files when asked.
- Now go to Firefox's Downloads and resume the download.
Enjoy :)
