Helllppp!

I just started using wordpress and I was playing around with the site when I found the general options tab. I changed the link on the top left of my page to all caps because that is how i would like my site name to be shown. i also changed my wordpress URL to all caps and that is where I messed up my site (ex. http://www.hello.com/oops ->www.hello.com/OOPS) . The page seemed to loose its style sheet so I tried to change it back and it did not save. now everytime i go to log on it looks like it cannot connect to the style sheet and will not allow me to get back in to my wordpress site manager. It shows the wordpress login page but i get a PAGE NOT FOUND when I enter my login info and press login.

HELLLPPPP!!!! haha some guidance would be greatly appreciated.

Thanks