How to Recover Lost Passwords in Microsoft SQL Server
Start by launching SQL Server Password Recovery software. Next Click on Browse to select MDF files.
Choose the MDF files from the system directory. Click Open to confirm your selection
Next step is to select the desired user for which you want to reset the password
Now Click on the Change Password box and type a new password for the selected user
Now Select 'Change Password' for resetting the password for the user account
After the new password has been set for the selected user, Click OK to finish.