1. Click your 'Start' menu and click 'Control Panel.'
2. Click 'Programs' and click 'Programs and Features.'

3. Scroll down to 'Microsoft .NET Framework.' Uninstall each version by clicking the 'Uninstall' button on top of the list of programs with each version selected.
4. Click the first link in Resources to get to the download page for the .NET Framework. Wait for the download to start and choose where to save the file.
5. Double-click the installer from the location you downloaded it to. Click 'Next' and follow the installation instructions until you must click 'Finish.' Click the button and restart your computer.