ok, I have downloaded mirc after being away from it for several years, when I click run it pops up a little box asking for a password. as if its locked. I get no menu no login options, just that box. doesn't even give me the option to reset or anything. what do I do?

That sounds like mIRC's lock feature which allows you to set a password for some functions (or for mIRC as a whole). To reset the password follow the instructions here.