If you are faceig issue to using facebook messanger then you can restart you device after that check its resolve or not. If not, then you can clear data and chache of the application if you dont know about how to resolve your Facebook Messanger Problem by using this trick then follow this steps:

Got to the Setting & click on the application 

Go Device app section and click on facebook messanger 

Then you can see there clear chache and clear data. 

Then opn the application and your facebook Messanger problem is resolved