If you have backed up your cards by registering an account please uninstall mobile-pocket; then re-install it  and log into the app with your credentials, as usual. To activate the lock feature in mobile-pocket just set up a new PIN-code.
If you have not registered an account yet or if you are not sure about it send us 3 or 4 barcode numbers and names of cards you have saved in your account either through the in-app support chat (you can find this under “settings” and “help”) or via e-mail to help@mobile-pocket.com.
We will search for your cards and help you with the further steps.