World will not load in singleplayer

When I went on MC 1.12 for the first time i was very exited, don't get me wrong, i expected it to work instantly. Instead it had been stuck on the loading screen to one of my survival worlds for 20 or so minutes. So I tried to restart the game but it would not close down. When i restarted the WHOLE system I went onto Hypixel, it worked.SO i tried again...nothing.

P.S.I do not know if anyone else has this problem.