Restoring the Database and Log Backups 
Prerequisites
The following explanation of the restore procedure assumes that you have set up your R/3 System on at least three disks as recommended by SAP and that the disk referred to as the
executables disk is still accessible. This disk contains the SQL Server executables that enable the use of the Enterprise Manager and the msdb database that keeps a record of all backups that have been made. Both the Enterprise Manager and the msdb database must be accessible to enable the restore operation described here.The overall restore process consists of several restore phases. If you do not have valid transaction log backups the restore process may consist of only one phase.
Phases

It is absolutely vital to ensure that the correct restore option is set for the restore phases.
·
For the last step of the overall restore process you have to set the restore option·
For all other restore operations you have to set the option:
In the following procedure you first restore the most recent database backup and then the succeeding transaction logs. During the entire procedure, do not execute any transactions and do not shut down the database server. A Server shutdown would write a checkpoint to the log and, as a result, it would not be possible to restore further transaction logs.
Procedure
The Restore Database dialog box opens.
Force Restore over Existing Database
Leave database operational. No additional transaction logs can be restored.
All the backups that are necessary to restore the <SAPSID> database are now displayed in a list. This list is generated from the backup history that is stored in the msdb database. Check that no backup is missing from the list, especially the last transaction log backup.

If backup history in the msdb database is not up to date then you have to restore the database and all the succeeding transaction log backups from device. In this case, follow the instructions given in
Restoring a Backup from Device.
If only the last transaction log backup is missing from the list of backups suggested for the restore operation, proceed as follows:
·
Change the restore options in the Options tab to:·
Continue with steps 6 and7.·
Restore the last transaction log from device. Follow the instructions given in the section Restoring a Backup from Device. Note that for this last step it is essential to change the restore option to Leave database operational. No additional transaction logs can be restored.
To find out the label of a tape you have to insert, select the required backup from the list and choose Properties. A window with information about the backup opens. Media Name shows the label of the tape.
The data from the database backup is copied to the disk and the succeeding log backups are applied to the database.