Issue with Facebook Marketplace

Hello, I'm really clueless when it comes to social media! If you could help me!!
I have a problem with MarketPlace on Facebook, as I want to contact individuals. I've tried several times to send them messages (they show up in my inbox but when I click on them.... I can't see my messages because the page redirects me to a page that says "New accounts can’t be created right now," while I don't want to change accounts, I just want to see my messages!!)
And now, when I click on the listings where I've sent messages, it says "this page is not available, the link may be broken or the page may have been removed." Whereas on other listings, I can navigate around.
I'm quite urgent, so if you could help me!! Thank you all