Windows XP doesn't boot anymore?

Ok so yesterday, i left my laptop to get some Windows upgrade, and today in the morning I checked my laptop for the upgrade, and instead it showed me that Windows didn't start succesfully, and some other options, everytime I choose any option a blue screen shows up and restarts again with the same options. So I got the ERD Commander in a CD disc and booted it in my laptop but the OS won't show, it was operating on /C so what can I do now? I don't have the repair disc either, i hardly know about computers, please help!!