Hi,
This folder is the default location for SQL Server database files created during installation. If you do not have database backup files, you should not be able to restore them.
SQL Server defaults to MSSQL\Data.
Also you mentioned MySQL Data whether it refers to the MySQL database.
https://stackoverflow.com/questions/3317926/how-did-my-mysql-database-get-deleted-automatically
Hope this helps and please help to accept as Answer if the response is useful.
Best Regards,
Carl