If all you have is the snapshot file, you can't use it to restore a database, since its files will only contain those pages that have been changed in the original since you created the snapshot.
But if you want to revert a database to the point in time when you created the snapshot, you can use your snapshot in a RESTORE command:
RESTORE DATABASE database_name FROM DATABASE_SNAPSHOT = 'database_snapshot_name'
There's an SQL Server Central article about database snapshots, how they are built and how they are used to revert a db: https://www.sqlservercentral.com/articles/database-snapshots-1
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