Gallery File Recovery
Some Android users have run into an issue with the Gallery. Some sketches that were once stored there have vanished. We posted a temporary solution for this on the SketchBook Pro Forum. However, in this release (version 5.2.2), we were able to address the issue.
We added a mechanism that searches for lost sketches. When any are found, it notifies you.
The retrieved files are then stored in a new Gallery folder, called Recovered. The process can take a few minutes depending on the size and number of files. Once the images are recovered, tap the Go to Folder button to open that folder and see the files.
Since the original file names have been lost, the files are named using the date found, followed by "recovered", and a sequence number. For example, 021520recovered1 for the first image found and 021520recovered2 for the second.
Manually recovering images
In the future, if you notice images missing, you can manually recover them by visiting your Preferences menu.
Tap
and select 
Preferences.Scroll down to the Gallery section and tap Check for Recoverable Images.
If the app finds anything, either tap Go to Gallery to see what it found or Later to continue sketching.
Note:If there are no images found, under Gallery in the preferences, it will say, No recoverable images found.