WTF! I have no rear break!

ok ok, i know this should be a simple one, but ive tried it all, hammer, visegrips, wd-40, shear patience and time....NOTHING has worked to loosen my rear break cable from the doodad ....ive even stood on my rear break lever! ideas? anyone had this one happen to them before? if so what was the fix? Also, how do i find out exactly which break shoes i need? I havent a clue exactly what these wheels are off of, and ive previously tried 3 different sets, none of which worked....i seriously am in need of some help! Thanks!