changed blog adres in “options” and blog crashed

hey,
i’ve changed an adres of my blog in the “options” section, and right now my blog does not work at all. <i’ve could make a typo>

can i bring it back to life or this is a “drop dead” situation ???
when i try to log in i’m receiving –>
Fatal error: Call to undefined function: nocache_headers() in /blog/wp-login.php on line 10

thanks in advance.
marcin