I have an LG G5. I recorded a video interview I had with Bruce Campbell. The video was slightly over 20 minutes long recording at 1080p at 60fps. I noted while it was recording that the video was automatically split into two separate videos. The first video is the lion share of length at about 20 minutes long and around 4gb in size if I recall correctly. The second video is about 17 seconds long. A few days after the interview the audio on my phone stopped working. I was googling around how to fix the issue and I saw that factory resetting the phone was a common fix. I did a factory reset, it said that it would not affect data on the SD card. After the factory reset the 17 second video appears to be intact and working. The longer 20 minute video seems to show a file size of 0kb in the file manager. Whenever I try to play the video I get a message that says Android does not recognize the video file type. I have been doing some googling around and thankfully there does seem to be ways to recover lost data from an Android phone after a factory reset. What I am looking to do is recover the lost video that was in the Android Phone after the factory reset. Thank you for your help, I will gladly provide any further information or screenshots if you need them.
NOTE: I am not sure if this will work, this works if file is deleted or when sometimes files just dissapear(It has happened to me).
IMPORTANT: DO NOT USE YOUR SD CARD TO STORE ANYTHING NEW, IT CAN/MIGHT OVERWRITE YOUR DELETED/LOST FILE
Put it on your computer and use a specialised software for file recovery(try Recuva by Piriform, here: https://www.piriform.com/recuva). It will the SD card for any deleted/lost files it can find and you can recover them.