I am not sure I understand the question. PHP is not a database or a file format. Do you want to convert from MySQL to Microsoft SQL Server? If so, this can be done via several methods.
I have done backup from VPS account. Now it says that this is PHP file. How can I change from PHP to SQL, because it says that SQL format is needed to restore the backup file.
if you backup a mysql database you get it in .sql format or any other compressed formats depending on how you backed it up.