I’m sorry that this is happening! What a terrible first day using the app! The other responder is incorrect about a few things. Obviously you don’t have any local backups if you just started using the app.
There may be a server side backup available, especially if you’ve been using your AnkiWeb account actively. @dae will be able to check for that the next time he’s online. He will let you know if one is available and confirm if you want him to restore that on AnkiWeb. It won’t necessarily be from the last day or 2, but it sounds like that might be your only option, if you’ve never synced with any other devices.