You can contact Facebook and let them know that your website URL has been blocked. In other words, one of the most reliable ways that can be used to get a website unblocked from Facebook is to contact them.
There are two ways that this can be done. If there is no message that is alerting the person who manages the page that the website has been blocked, then that person will need to go through the contact forms located on the “Help” page.
If there is a message that alerts users to the fact that a website has been banned, then the first thing that needs to be done is to click on the “Let Us Know” link that is located at the bottom of the message.
This button will lead to a form that can be used to contact Facebook and inform them of the precise problem, as well as alert them to the fact that the URL is not spam. The reply times differ from person to person, but this is definitely the first step that anyone can try.
Also try this method
You can also appeal to friends, family, and customers that is if it seems as though Facebook is not taking notice of the fact that the website has been blocked, then it might be time to contact friends, family, and customers and ask them to also contact the company on your behalf.
This will result in a greater number of messages being sent to Facebook about the problem, which will force a greater amount of attention to be paid to the problem. This does not produce immediate results, but will usually cause Facebook to work more quickly to unblock the URL.