Need to find out the historic information of backups , try this script
SELECTCONVERT(CHAR(100), SERVERPROPERTY('Servername')) AS Server,msdb.dbo.backupset.database_name,msdb.dbo.backupset.backup_start_date,msdb.dbo.backupset.backup_finish_date,msdb.dbo.backupset.expiration_date,CASE msdb..backupset.typeWHEN 'D' THEN 'Database'WHEN 'L' THEN 'Log'END AS backup_type,msdb.dbo.backupset.backup_size,msdb.dbo.backupmediafamily.logical_device_name,msdb.dbo.backupmediafamily.physical_device_name,msdb.dbo.backupset.name AS backupset_name,msdb.dbo.backupset.descriptionFROM msdb.dbo.backupmediafamilyINNER JOIN msdb.dbo.backupset ON msdb.dbo.backupmediafamily.media_set_id = msdb.dbo.backupset.media_set_idWHERE (CONVERT(datetime, msdb.dbo.backupset.backup_start_date, 102) >= GETDATE() - 7)ORDER BYmsdb.dbo.backupset.database_name,msdb.dbo.backupset.backup_finish_date