Need help in URL reference

I messed up my installation after I tried to change the display URL for wordpress in Tools->General settings.

There was an error after I click update and I guess it messed things up. Now my blog site displays without any CSS styling.
Besides that, I directed to a 404 page when I try to access the log in page, even though I’m sure the file is there through FTP.

I guess I need to modify the file path or something back to the original. Anyone knows where to modify it? Or is there another solution to it?