No thumbnails on Facebook Posts

Now I know there are a whole load of posts about this already but I’ve been through them all and none have worked!

I’ve literally installed every single plugin to do with meta stuff and thumbnails and sharing and facebook and still there is nothing coming up on facebook, just an ugly link!

I’m very new to this and don’t yet understand technical terms and have no idea when it comes to changing code so if anyone can help I’d really appreciate it!