Try going to _Settings_, then _Password_. Enter your lock screen password. Swipe down there are radio buttons under a heading that reads _Allow access when locked_. The last one is _Reply with message_. Try turning that one off.

If problem persists and you want an annoying non(long-term)solution, you can swipe right directly on the lock screen text to get a reply square. Selecting this will allow you to close out of the lock screen text and give you full access to the password entry screen so that you don't have to restart your phone.