gets stuck on mojang loading screen

So I open the launcher and that works fine, and then when I click play it shows the red mojang logo and gets stuck loading. I use a windows 10 computer. This problem only started happening about a week ago, before that it loaded and worked great. If I click the screen while it is stuck a box appears saying that there was an unexpected problem and gives me two options to either A close the game, or B let it run and see what happens (not those exact words). When I press close the game it says something about sending a complaint to microsoft and then it reopens the launcher with a box that says something along the lines of "unexpected problem occurred sorry for the whatever" pls fix