First of all:
Any one give me a proper solution.
Well, define 'proper solution'. After that, no need to use bold for it. If you have an issue and you are here for help, please be a little respectful.
"Failed to update .mdf database because the database is read-only"
A simple Google search
] could had given you many links like this:
based on what you say, and the discussion link above, Win7 & Vista has some extra security layer and you need to give proper permissions to the user who is trying to access the database. It's a security configuration issue.
(BTW, I think, you should get the details of this privilege issue in EventViewer logged as an error.)