我认为您需要为php5安装MCrypt模块. 按照步骤

i think you need to install MCrypt module for php5. Follow the step

 sudo apt-get install php5-mcrypt

当您不正确地删除php pakage时，可能会发生这种情况 希望这能解决您的问题

This might happen when you remove php pakage improperly Hope this will resolve your problem