Apologies for the trouble.
These are known issues with the last update of Lightroom.
Would suggest you to follow the below steps :
Many, many people have had issues with 2015.2 and 2015.2.1 and Adobe has apologized for the mess it has created (Google to learn more). Revert back to CC 2015.1.1: http://www.lightroomqueen.com/how-do-i-roll-back-to-lightroom-2015-1-1-or-lightroom-6-1-1/. CC 2015.3 is rumored to be coming soon, but be patient and wait a few weeks before updating to it -- let others do the beta testing.