gavrai, welcome to the SevenForums
If you have access to the internet as it would appear with this post, then go to Ubuntu.com, and download the OS, then create a start up disc (Ubuntu will allow you to make a disc that loads up the Linux OS without having to install the complete OS. Then backup the files you want to save, now you can reinstall or repair your windows system. Put the Ubuntu disc some place safe just in case you did it again later.