Magento: Fatal error call to undefined function curl_setopt() in curl.php

If your magento page display this error so please check CURL is enable or not in php.ini file.

If not then enable curl in php.ini file.

Please find "extension=php_curl.dll" in php.ini file. And remove ";" from starting. Like below: 

;extension=php_curl.dll
to
extension=php_curl.dll