can't play ANY minecraft world that i made anymore

(sorry if it comes out rude. my apologies) hello, i have an VERY IRRITATING issue! i CAN'T play ANY of my minecraft worlds anymore! at the start screen with mojang on it it KEEPS loading, if i click on the right it says: Java(TM) Platform SE doesn't react. if i click on close this application it starts up. if i choose singleplayer and click on a world and then on play world it KEEPS loading! can you PLEASE fix this? i beg you. i REALLY want to play Minecraft 1.12.2. i beg you, PLEASE help me! (i'm dutch by the way but i hope you get to understand the screenshot i sended with this)