webpage blank

hi.
i was trying to fix a login problem and in the process i accessed ftp. i renamed the plugin folder and theme folder to try to resolve the issue and when i was able to log back in i switched the names back to the original names. i dont think i messed around anything else. i also was in php myadmin but i dont think i made any changes there.
since then my website is white/blank. also i have no themes downloaded or plugins/widgets. i tried downloading a new theme but it fails.

any ideas? thanks.