Is there any Text messaging app that will allow me to put a lock on all my text messages?
1. From the home screen, touch messaging.
2. Open the thread (contact’s name) that you want to lock.
3. Press and hold the message.
4. Select ‘Lock message’ (a lock will appear next to the message if it’s locked).
5. To unlock the message press and hold the locked message and choose ‘Unlock message’.
Not sure you can lock individual apps but you can lock your phone.
tap menu, tap settings, tap location & security, tap set unlock pattern
Hope this helps.