Explanation :
In the event of complete loss of your database, you will need to first restore the database spfile. Once you have restored the database spfile, you will need to restore the database control file. Having restored the database control file, you would restore the database and then recover the database. Finally, since this would be an incomplete recovery (because you lost the entire database, the online redo logs are gone too), you would need to open the database using the ALTER DATABASE OPEN RESETLOGS command.