If you're lucky (and you've got a version of windows that supports this), your PC may have created a restore point. Go to Control Panel>Performance and Maintenance and click system restore, you should be able to reatore your PC to a pre-ripper state. (Look in help for "system restore" if you can't find the wizard this way). If this doesn't work, there's still probably something you can do, but it'll take one of the more technical bods on here to tell you what to do!