Samsung s8 plus deleting downloaded files mp4

[Android Central Question]

I downloaded 30 mp4 files from my laptop and the next day they are no longer there. I have tried 2 different file locations on my phone for the same result. This really annoying.

 

[B. Diddy]

Welcome to Android Central! Do you remember where you copied those mp4 files to? If you copied them to an SD card, the card might be corrupt or counterfeit. If you copied them to the /Download directory, certain "phone cleaner" apps can automatically clear out that directory, depending on their options.