@karismacharm: Try pressing the Volume Down and Side Keys together for around 10 seconds until the phone restarts to see if this helps. If you have any shortcuts in the bottom left or right corner of the lock screen, try tapping one of them to see if it launches the app. If the phone remains unresponsive, reach out to our Help Desk on 0333 000 0333, or on Facebook or Twitter, and an advisor will be able to assist you further, and arrange any necessary repairs.
