I can get into admin using the url I posted above please follow the upgrade install documentation to install your xml plugins. You deleted your install directory before completing the install correctly.
IMPORTANT - FOR XENFORO CUSTOMERS ONLY.
1. Upload the library directory from our install directory to your xenforo directory it contains necessary files for the addon code.
Make sure to set all xml files in the install directory to 777
2. Go to your admin panel ( http://www.yoursite.com/classifieds/adm-index.php ) and select the generate xml plugin link to generate your xenforo plugin which adds the navigation.
3. Install that generated product-xenforo.xml file to your xenforo under install addons.
4. You may not delete the install directory as per the main direction point number 5.