Hi Mary,
We’re sorry for the inconvenience here, but it’s not available to retrieve the website back if it already has been deleted.
In this situation, I suggest you sign up a new trial subscription, then use the backup data you saved before to design your new website, also I suggest you use SharePoint WorkSpace (Which is included in Office Professional Plus 2010 provided by Office 365 for Enterprise subscription) to back up all the data in your SharePoint Online sites in case the the same situation happen again.