I don’t see why that would have broken anything. I’ve never done that before. I’m pretty sure on that old version of Mac OS you could’ve just run resetpassword in terminal to have reset it. But maybe that’s only on the dvd.
Well as long as disk utility works find an iso of whatever Mac OS you want to run and burn that to a USB drive. 10.6 is my favorite since it still has Rosetta to run old PPC OSX software, has the old look, but has the best software support.