Customization not working

Hi, I am unable to access Customization facility. The Appearance-Customization and Customize This Site buttons give me this message. The defaoitejewellery.com page isn’t working - defaoitejewellery.com is currently unable to handle this request. It happens after I install plugins (Contact Form 7 and Clean and Simple Contact Form) It works again when I deactivate the plugins. I have been unable to connect JetPack on this theme even though I have a valid wp.com user name I am just starting with WordPress.org, I want a simple contact page, help please D