If you can't find the pictures and videos, then use the AppLock's recovery feature. The application is said to recover files that have been lost or deleted from the Vault. Secondly, make sure that you files are not locked. While a file is locked, it won't be externally visible except the Vault.
If you have additional issues with the application, I recommend you report the bugs and problems directly to the developers of the application. You can use the following email address to send your inquiries: