LR catalogue doesn't open

Yesterday I closed lightroom, got the question if I wanted to quit, I said yes. Today I'm trying to open LR and only get a message that the catalogue I'm trying to open is already open in an other session, that I shoul close that session. But I didn´t open it anywhere else. If I try to open the older version, I get the message that there is a an updated version of my catalogue, that I should open that. If I try it, I again get the first message and there is no way that LR will open.