I am not able to use the back button or access indiidual people in my text messages

[AC Question]

This has just started. it seems random but at times I am not able to use the back button on my lg leon phone. the home button and the button to show all items works but that's it. When this happens I also cannot access sub menus from with in applications such as when I go into messaging I cannot select a person to message back If I press on their name nothing happens. Help