What are some things i can do at home to find out for sure if i torn my acl??it doesn't feel like i did?

but i didn't hear a pop when i fell nor did i cry.I cant touch my with my leg..n my knee doesn't seem to give out on me,it just get stiff but i don't know if its fluid.do u think it torn or what can i do to find out for sure?my mri says its completely torn..but i don't believe it.