Make use of guide below from Microsoft or use another way https://www.repairtoolbox.com/projectrepair.html
Project Repair Toolbox
To restore the Project Server database, you can use the restore feature of Microsoft SQL Server. After you restore the database, you must delete and then re-create the MSProjectServerUser and MSProjectUser accounts to make sure that the correct passwords are configured. To do this, follow these steps:
1. Click Start, point to Programs, point to Microsoft SQL Server, and then click Enterprise Manager.
2. Expand Microsoft SQL Servers, expand SQL Server Group, expand your Microsoft Project Server database server, and then expand Databases.
3. Right-click the Microsoft Project Server database, point to All Tasks, and then click Restore Database.
4. From the list of backups, click the backup to restore, and then click OK to start the restore.
5. Click OK to confirm that the restore completed successfully.
To delete and re-create the database users, follow these steps:
1. Expand your restored Project Server database.
2. Click Users, and then click the MSProjectServerUser user.
3. Press DELETE, and then click Yes to confirm the deletion.
4. Click MSProjectUser, and then press DELETE.
5. Click Yes to confirm the deletion.
6. Right-click Users, and then click New Database User.
7. Under Login name, click MSProjectServerUser, and then under Database role membership selectMSProjectServerRole.
8. Click OK.
9. Right-click Users, and then click New Database User.
10. Under Login name, click MSProjectUser, and then under Database role membership select MSProjectRole.
11. Click OK.
12. Log on to Microsoft Project Web Access to verify the connection.