To install of iLock, the iPhone has to be jailbroken and you can purchase it via Cydia.

After configuring of it, you need to do respring. Otherwise, lock screen won’t work at all.

If there is a problem with the iLock, there are couple of things to recover. The easiest way is to make a call from other phone to the problematic iPhone. After answering of the call, you can press home button to navigate iPhone apps. Then, you can reconfigure of it. If it is not working, do ssh and do “rm -f /var/mobile/Library/Preferences/com.sicmobile.ilock.*.plist; killall SpringBoard” to remove all, which eliminate all configuration from iLock.