I had a similar problem some time ago. The Business was not happy to allow the Extended SP's to be enabled.
I use this to get the latest backup for a given database rather than folder scanning. It give the physical location that you can plug into the restore statement.
SELECT TOP (1)
, cast(bs.backup_size / 1024 / 1024 / 1024 AS decimal(8, 2)) AS Size
, cast(bs.compressed_backup_size / 1024 / 1024 / 1024 AS decimal(8, 2)) AS [Size on Disk]
FROM msdb.dbo.backupset AS bs
JOIN msdb.dbo.backupmediafamily AS bmf
ON bmf.media_set_id = bs.media_set_id
WHERE bs.database_name = 'MyDatabase'
AND bs.type = 'D'
ORDER BY bs.backup_finish_date DESC;
DBA (Dogsbody with Bad Attitude)