Cannot Access Admin Site Anymore

I was in the ‘general settings’ of the admin area to modify my tag line. When I saved the changes and the screen refreshed, the screen showed a “404 Error”- that the page could not be found.

When I tried to reenter my password through the wp-admin site I’d bookmarked, the site does not look like the normal login page. When I enter my password/id info, the contents of the site come up but they are all jumbled – and I cannot access the normal admin site anymore. The only thing that I can think of was that my finger touched the mouse pad and modified the web address somehow and I saved it- but I am not sure?

Is there a way for me to login and reset wp to an earlier edition, prior to my error?