There are two ways you can open myDeviceLock without using launcher icon:
1. Open from the browser:
On your device’s browser go to the following URL: mydevicelock.com/starter and click the link to open the app.
2. Open from the dialer: In your dialer app enter # and your PIN then tap Call button to open myDeviceLock. (for instance #0000 + Call button)
3. If Neither of these two methods doesn’t work.
Try to uninstall the app and reinstall
Go to your device Settings > Apps > find myDeviceLock in the app list and tap UNINSTALL button.