itunes erases its own library an 2 files on my computer

i am gettin tired of itunes dumping its own library i open itunes or i am looking around and it dissapears and i hafta drag in my music again and again and again its getting annoying and its dumping 2 folders into my recycle bin itunes library extras and itunes library genius i am a beginner learner level on a computer i know some stuff some things but this is getting annoying how do i fix this i am logged in in itunes into my account and if i plug my ipod in it says i hafta erase my ipod and re sync it its a pain all the mumbo jumbo crap i am usinga toshiba laptop satellite m305-s4907 with windows vista home premium service pack 2 and itunes version 10.2.1.1 how can i fix this problem i recently had to erase my hard drive and reinstall windows and i had someone do it and i have a backup hard drive where i am putting the music onto my computer then into itunes this is crazy anyone kow how to fix this?
Ben B