my game updated and wont let me in a world

I logged onto Minecraft and I have it set to automatic download so it updated and when I went to load into the world it said there was a problem loading this world and I tried to restart Minecraft and restart my pc but nothing works is there any way you guys can help me I really need this world I've spent way too long on it and i cant lose it. it has a bunch of builds I made please help me