Safe Gallery Free-Photo/Movie for PC is a brilliant app, which is completely free, and does not hold back on any features. You get the complete package when you install it. This app allows the user to hide sensitive images and videos with a password, so that no one else can access them. You can manage entire albums with this app, and when you are viewing the albums, you can go through all images and videos effortlessly. The protection lock can be either a PIN code, password, or pattern.
There is one feature, which is very handy. If there is any media file that is not locked, and you inadvertently delete it, it gets deleted from the memory. But there is a very nifty feature on this app, which allows you to recover deleted files, and get them back. There is a Lock Media Recovery option which allows full recovery of lost images and other media.