Cant' uninstall app; it shows up on home screen but not app drawer or installed apps list
Is the app in this question the same as the one you're talking about? If so, you might be dealing with malware.

The reason the app might not be showing up in the installed apps list in the Google Play Store is because it was installed outside of the Google Play Store (by a different app). Try finding the app in the installed applications list of Android itself. Do this like so:


Open the Settings app.
Scroll down to Apps.
In the top right corner, click ... and then Show system apps.
Search for the app name in the list, presumably APP Lock, and select it.


Have you found it? Great! Uninstall it by clicking Uninstall.
If this button is greyed out, then the app might have installed itself as a system app and you will need root to remove it with Root Uninstaller, for example.