Hi,
Taking a gamble that you mean that there is no keyboard showing when you wish to type in a message or similar.
1. Try a'' soft reset'' - if that doesn't work.
2. Try a ''master reset''.
''Be aware that a master reset will erase all your downloaded apps and user data. It will restore your phone to a factory default condition. It will be like when you first bought it. ''
Before you perform a master(factory) reset ensure that the battery is charged. Do not leave the charger connected when you perform a master reset. Remove the external SD Card (if any installed).
Here is a link that shows how to do a soft reset and a master reset. '''Do the soft reset first '''and see if it solves your problem.
https://www.youtube.com/watch?v=HFAg76z2gXk