@Deborah84
Similar cases repeatedly come up on this forum, and from what I have seen, they are usually from new hosts. Although there are really wonderful and lovely guests out there making hosting worth it, there are also 'guests' that in fact are scammers and prefer targetting inexperienced hosts.
So beware of anybody to get you to circumvent the safety of the Airbnb system or to tie an excuse on you that they paid but isn't showing blabla.
Despite all of the annoying and not working things and glitches on this site, Airbnb has the financials down to a pat! Why else would they be so huge 😉
If you don't have a confirmed reservation, they didn't pay and don't have a reservation. Tell them nicely but firmly you don't have a confirmation and can't do anything from your side, and that they have to sort out the details of their payment method with Airbnb directly.
If they start sending you inappropriate messages or suggesting payment in cash, don't react and report them by flagging them (little gray flag in upper right hand corner of message) so that Airbnb is alerted to the problem.
Hope this helps.