Go to Control Panel>Add or Remove Programs and then in the left-hand pane, click on "Add/Remove Windows Components."
Click on Accessories and Utilities, then on the Details button, then on "Accessories" and on the Details button again. If Calculator is unchecked, check it, click OK.
Then click on "Games" and the Details button. Put check marks in the boxes for the games you want to install.
Then click OK and OK and "Next." Step through the wizard to install everything you checked. Then go back and re-check them to re-install them.
If the calculator and the games are already checked, uncheck them, and step through the wizard to uninstall them, then go back and do the above steps to reinstall them.