When trying to open iTunes on PC, error message #7?

Trying to open iTunes on my Sony laptop, it won't open and says "Error Message 7" "Must re-install ITunes".It was fine earlier, until I did a required update. (these updates included other things such as Microsoft.) Question 1) If I delete iTunes, will it delete all the library and everything in it? (I ask this because it is my roomates iTunes, and can't recover anything, such as purchased music, or her iPhone backup.etc.) And question 2) how is this error bypassed? Maybe there's some sort of thing I can do to fix it? If you are familiar wirh this, Any help is appreciated. Uou don't have to know both answers, just need help As soon as possible.

There's a guide to troubleshooting this error message here: http://support.apple.com/.../kb/ts3074

This troubleshooting should not interfere with your backups or media library, but you might like to back them up elsewhere just in case. The location of your media lirary is described here: http://support.apple.com/.../kb/ht1391

And you can find out where your backups are stored as described here: http://support.apple.com/.../kb/ht4946

Hope this helps.