Screwed up adding image to post and site's down

I was attempting to insert an image into a post and I think I accidentally (boneheadedly) selected a library of images instead of ONE image. As a result the upload attempt was too large and it got hung up. I reset Safari and tried to get it to “forget” my mistake, but that didn’t work. I’m fairly new to the Mac environment so I don’t know how to troubleshoot these things as easily as if I were on a PC.

Now when I pull up my URL for the site, I get an internal error and can’t log in. Any ideas as to what I can do? Did I break my site for good? Thanks!