Surely you backed up all your important data prior to upgrading to Mavericks?
By the way, Mavericks is only available for download from the App Store, not the Apple website.
I installed Mavericks within five hours of the announcement. Backed up to Time machine first of course. Didn't need to as all was perfect.
Sometimes stuff happens. Its why they brought out Time Machine, best backup software in the world. I used it to wind back from ML to lion while they sorted the spotlight error. There should be no need to rebuild years of work.