You deleted wp-contents folder? - It is a mistake!
This is simple instructions, step by step in case of infection:
First - turn-off page in .htaccess file.
Next, check files by modyfication time and look into server logs.
Then, by FTP remove wp-admin and wp-config catalog ....and replace it by fresh copy from latest wp package. Replace all files in wp root directory.
Remove all plugins and upload a fresh copy's.
Check all non-modified files eg. wp-config.php, .htaccess, in themes (if possible, replace by a fresh/backup copy) and upload folder. Find and remove malicous code in non-modified files and remove all backdoors hidden in the new, non-standard files.
After cleaning, secure your wp - set permissions, add fixes to .htaccess, check your theme - if timthumb is used - update and secure it.
On end, turn-on your page.