When you restore the MDS database from some other computer, may be from different domain or from different computer where your username is not present, you will get error on web site as “Access Denied”. Or you will not see the “User and Group Permissions” link.
Reason for this is that since you have restored the MDS database from different domain or computer you username might not be present as administrator on MDS database. Solution is to change the administrator by following the below steps.
Execute the following command to change the administrator
EXEC [mdm].[udpSecuritySetAdministrator] @UserName='USERNAME', @SID = 'SID', @PromoteNonAdmin = 1
Steps to get SID
Open PowerShell command line and type the following command
$AdObj = New-Object System.Security.Principal.NTAccount("User or Group Name")
After performing above steps you should be able to access the MDS web page as administrator.