Hello @Phanu0,
You could try contacting Airbnb customer service to see if they can contact your guest.
In the text your guest sent did she agree and arrival time?
The post below has a list of phone numbers and details of other ways to contact them.
Contact-Airbnb-A-Community-Help-Guide
I see your check in time for your listings is "Anytime after 3pm". I realise you want to allow for guests arriving at different times on international flights but that's a very wide time range.
In other posts here I see hosts say that Airbnb has required them to be available to check the guest in at any time during their advertised check in time.
You could check what time most of your guests arrive. If most arrive sometime between 3pm and 8pm then set your check in time to that. You can always agree a later time with individual guests if you wish.
Having a check in start and end time limits the time you have to wait if a guest doesn't turn up.
Steve.