The App Lock app helps you to lock only the things you want to, like messages, gallery or an app. This app is free and password protection is availed for only apps you need to lock down. We tell you in steps on how to use it:
Search for App Lock in the Android Market and install it.
After launching the app, enter a password you can remember. This will be used in future unlocking (you can add password hints if you might forget the password).
In the application lock category, select the apps you need to lock down, you might also use the search button for finding the particular app.
You have a password alternative, pattern. Draw a pattern of your choice.
To save your apps from maliciously uninstalled, toggle to System Lock and enable it.
You can also set for the time you can stay unlocked after giving password once.
This app can give you and your Smartphone enough privacy it deserves. Best of luck guys!