Sorry this happened. Go to your
store account, log in (if you don't know or remember your password, have it emailed to you), find your Microstudio order number and click it. At the BOTTOM of the order page, you will find your Registration Code, RegEmail, and a link to download the latest code you have access to.
Download it to a folder, not the Desktop. Then double click it to run the installation, entering the RegCode and RegEmail in the appropriate fields.