/*
You need to reference the following:
* The target database i.e. the database you will restore to.
* The directory where the backup file is saved.
If you are using the Ola Hallengren backup scripts the directory path will look 
something like below.
\\ServerWhereBackupsAreSaved\DriveName\InstanceName\TargetDatabase\Full\

Find & Replace the follow text for the target database and directory:

TARGET_DATABASE
DIR_PATH
*/
/*
Declare Variables
*/
DECLARE @DatabaseToRestore AS VARCHAR(MAX);
DECLARE @DirToSearch AS VARCHAR(MAX);
DECLARE @ShellCommand AS VARCHAR(MAX);
DECLARE @BackupFile AS VARCHAR(MAX);
DECLARE @Sql AS VARCHAR(MAX);

/*
Set User Variables
*/
SET @DatabaseToRestore = 'TARGET_DATABASE';
SET @DirToSearch = 'DIR_PATH';
SET @ShellCommand = 'dir ' + @DirToSearch;

/*
Create Temp Table To Hold xp_cmdshell Output
*/
IF OBJECT_ID('tempdb..#DirList') IS NOT NULL
	DROP TABLE #DirList;

CREATE TABLE #DirList (
	Id INT identity(1, 1)
	,line NVARCHAR(1000)
	);

/*
Enable Advanced Options To Enable xp_cmdshell Temporarily
*/
EXEC master.dbo.sp_configure 'show advanced options'
	,1;

RECONFIGURE
WITH OVERRIDE;

EXEC master.dbo.sp_configure 'xp_cmdshell'
	,1;

RECONFIGURE
WITH OVERRIDE;

/*
Run The Shell Command To Capture And Write Dir Info To Temp Table
*/
SET @Sql = '
INSERT INTO #DirList (line)
EXEC xp_cmdshell ' + '''' + @ShellCommand + '''' + ';';

EXEC (@Sql);

EXEC master.dbo.sp_configure 'xp_cmdshell'
	,0;

/*
Disable Advanced Options And xp_cmdshell Again
*/
RECONFIGURE
WITH OVERRIDE;

EXEC master.dbo.sp_configure 'show advanced options'
	,0;

RECONFIGURE
WITH OVERRIDE;

/*
Get The Last Backup File Name And Save To A Variable
*/
WITH CTE
AS (
	SELECT SUBSTRING(line, 37, 100) [FileName]
	FROM #DirList
	WHERE Id > (
			SELECT MIN(Id)
			FROM #DirList
			WHERE line LIKE '%<DIR>%..%'
			)
		AND Id < (
			SELECT MAX(Id) - 2
			FROM #DirList
			)
	)
SELECT @BackupFile = [FileName]
FROM CTE
WHERE [FileName] = (
		SELECT MAX(FileName)
		FROM CTE
		);

/*
Create The Restore Script
*/
SET @BackupFile = @DirToSearch + @BackupFile
SET @Sql = '
ALTER DATABASE ' + QUOTENAME(@DatabaseToRestore) + ' SET SINGLE_USER WITH ROLLBACK IMMEDIATE;
RESTORE DATABASE ' + QUOTENAME(@DatabaseToRestore) + ' FROM DISK = ' + '''' + @BackupFile + '''' + '
WITH NORECOVERY
,REPLACE;
RESTORE DATABASE ' + QUOTENAME(@DatabaseToRestore) + ' WITH RECOVERY;
'

/*
To Directly Execute The Script Uncomment The EXEC Statement And Delete The Select Statement
*/
/*
EXEC (@Sql)
*/
SELECT @Sql