Read Data from registry

Hi
This may sound a little dumb but i cant find a way to read data from registry during uninstall of an application. I made a registry entry during installation and now i want to read it when i run the setup again for upgrade or uninstalling the application. I want to lkeep the stored registry value in a property. Can anyone help me with it?

P:S I am working on a basic MSI project.

Thanks