Hi Muhammad,
Sorry to hear that your site's been blocked by Facebook. That's terrible!
I haven't dealt with this myself, but I did some digging and it looks like you aren't alone. Unfortunately, it looks like it's also very hard to get Facebook to unblock you. Facebook uses the companies Securi Site Check to make sure sites aren't scammy, spammy, or hacked. Securi looks like an aggregator of many security check sites, but that it will tell you which security check sites still have you on their blacklist and which ones you need to reach out to get whitelisted. You'll want to do this first before you do anymore outreach to Facebook.
After you are sure you're whitelisted with the security check sites, then contact Facebook. I found this case in Facebook's help threads about a company that was able to successfully unblock their site. Looks like he had his brand "like" all of Facebook's official pages to help businesses, which sent a trust signal to Facebook that the brand was legit. and then commented on all of them to get his page unblocked. Sadly, it looks like you have to be a very squeaky wheel to get anything done. If you have a Facebook ad rep, you also might reach out to them after making sure your site's whitelisted on those security sites.
Sadly, it does look like people did end up switching domains or doing some redirect action when Facebook wouldn't unblock their sites. But I'd use that as your very last resort.
Best of luck!