I press play and it doesnt open

So, on sunday the tenth I was playing on Mineplex (a minecraft server) with my friends than about 1:30 it crashed and sometimes it randomly crashes but now I open up the launcher, I sign in (if I need to) then i press play it downloads closes then poof! Nothing! It doesnt matter if I sign into my sister's account, switch versions or anything. I have tried to backup my minecraft then delete it and redownload it nothing works please help me.