Fatal Error upon installing plugin

After installing the plugin on my wordpress blog, http://www.autobuyersecrets.com

Im getting the following fatal error:

Fatal error: Call to undefined function get_current_screen() in /home/jojotogo/public_html/autobuyersecrets.com/wp-content/plugins/pay-with-a-like/pay-with-a-like.php on line 988

Please let me know how to fix this as soon as possible as the site is now not responding. I cannot de-activate the plugin or access pages or posts, setting etc..

many thanks