Just gone on FB and tapped "Help Centre" and that's what came up. No sign of what you have been seeing.
The Help Centre is with the list of friends, messages etc.
Also please tell which device you're using (PC, phone, tablet, etc) and which browser (internet Explorer, Firefox, Chrome, Safari, Dolphin, etc) - or are you using a dedicated Facebook app?
It's pointless us coming up with suggestions relating to Internet Explorer on a PC if you're using a Facebook app on an Android phone!
I'm using Firefox on a PC. I type "Help Center" in the Search Facebook space. "Help Center" appears momentarily, then it changes to "Airbnb" and I'm connected to Airbnb.
The search facebook space is for finding pages and people. There are many pages with help centre (or center) as part of their name and this is what you will find. Click on the drip down arrow, far right of the blue bar and help is one of the options
Thanks very much, all of you. Problem solved (though I still don't know how "Airbnb" got into the act - not that it matters). And, woofgang, that arrow is hard to see.