What were you thinking when you tied your shoes? There's no way you concocted a knot so complicated, but your attempt to prevent your sneakers from coming untied has somehow changed into a convoluted puzzle too difficult and tight for your fingers to work through.
There is an easy solution for such a seemingly difficult problem. A light dusting of talcum powder on a stubbornly tight knot in a shoelace or other fabric string can make it easier to loosen and untie. Just stick with the double-knot next time you lace up your sneakers -- or keep a supply of talcum powder handy!