Anyone having problems with the Lollipop upgrade? The upgrade really drains my battery--still don't know why. I am not pleased with how the messenger was revised. It's clumsy.
Boot to recovery. Clear the system cache. (NOT factory reset.)
Can't do anything about Messenger unless you backed up the old version. Try GO SMS Pro, Textra SMS, some 3rd party app. I still haven't seen one I like, from the stock Google one in Gingerbread to the latest ones. I use Messaging 4.4.4 because it's the one I dislike the least. My wife likes it - she's on it all day, talking to the scattered family. (Facebook too, and I run the app once a week, at most.)
It's all personal taste. AFAIC, some people at Google have none. Then again, some people loved the programs I wrote, and some couldn't stand them. The last person who pleased everyone doesn't have living grandparents yet.