Media uploading broken

Hi I am using the Responsive theme but I installed Twenty Twelve to see if I got the same problem and I did. I tried to install a child theme and front-page.php to get additonal homepage widgets as advised at
http://themeid.com/docs/adding-additional-widgets/ This messed up my site so I recopied my child theme to my site and everything was ok but the media file uploading feature.

I have been talking to my web host, Dreamhost, and they advised me to add code to my htaccess file which corrected part of the problem but my media file uploading still does not work. The uploaded files re blurry and they don’t show up when I place them in my site.

Do you have any suggestions?

Do I have to redownload WordPress. If I save a copy of my wp-config and wp-content files and the contents of my child-theme folder, will I be able to restore my site if I redownload WP?