Restarting Interrupted Restore Operations in SQL Server
If a restore operation is interrupted, you can restart the operation from the point of interruption. This can be useful if you restore large databases. If the restore fails near the end of the restore operation, usually, you can restart the restore operation from where it left off, instead of restoring the whole database from the start. In particular, when you restore from tapes, you can restart on the current tape, instead of on the first tape. If restore was in the redo phase (being rolled forward), no data has to be copied from the backup set.
To restart an interrupted restore operation