Download the picture I uploaded

Stuff happens. Data can get lost or corrupted without your knowledge.

Copies of your original images should be stored on backup drives or uploaded to cloud storage.

I use Backblaze backup & recovery service.  But there are others like DropBox and Google Drive.  

As a computer user, you must have a backup strategy to protect yourself from data loss. 

In addition: in very few cases is the uploaded file the original file. 

I recommend, you start looking for a good back-up solution to avoid such issues in the future.