To Backup and Restore MSSQL Databases in Plesk 12.X, please follow the following these simple steps :-
To back up MS SQL database:
1) Login to Plesk control panel.
2) Click on "Websites & Domains".
3) Click on "BackupManager".
4) Click on "More Actions" and click "Database Backup Repository".
5) Click on "Back Up"
6) Select a Database and Specify the name of the backup file.
7) Press Ok.
To restore MSSQL database:
1) Login to Plesk control panel.
2) Click on "Websites & Domains".
3) Click on "BackupManager".
4) Click on "More Actions" and click "Database Backup Repository".
5) Click on "Upload Backup File."
Note : You can upload .bak file only.
6) Click on Browse to select the “Backup” file from your Local computer.
7) Press Ok.