problem after editing appearance coding

hey i recently installed word press to create a blog for a new website i am creating and after being given the theme twentyten by default i saw it did not look like how my current site looked so i started going through all the appearance files and editing them.

i got really far and made some great progress and then all of a sudden i edited something and then something went horribly wrong and now the page my site was hosted on… geoentertainment.co.uk/blogs … and the page after you log in would not load so now i cannot log in to my wordpress site to edit the changes to get it fixed.

i know from now on i should always back up my files and stuff before making edits and then i would not have this problem but is there anyway at all i would be able to fix the site?

or is there a way I can start again from scratch by re-installing the files to my web hosting?

thanks