Here, I will explain how to restore an SQL Server database from a backup file (.bak) file using SQL Server Management Studio (SSMS)
Step 1: Open SQL Server Management Studio
Step 2: Login with your credentials
Step 3: Right click on Databases node in the Object Explore and select Restore Database
Step 4: Click on Device in the Source section and click on browse button (…) to select your backup file.
Step 5: Click on Add button to select the backup file(.bak) then click OK.
Default name of the destination database will be the same as in the backup file. You can change it in the Destination section.
Step 6: Click on File tab, select Relocate all files to folder then select folder where you want to restore your database.
Default location of the restored database is the data directory of the SQL Server. To change it you need to follow this step. Otherwise you can skip this step.
Step 7: Click on OK to complete restore.