[Plugin: WP-Optimize] Error

After using it , my website went down, erorr 500 is throwm, please help,

unble to connect to database is the message displayed when i try to access my wordpress dashboard through administrative inerface of web server

I selected all the four check boxes and clicked the process button, everything was fine,and no error message, but, thence , when i try to access my website error 500 is thrown. My wordpress dashboard not opening and the message thrown is unable to connect to database.