1 GB is missed

my hardisk was 3.2 GB,i tried to install windows 2000 advanced server,then i changed my mind after starting,then i found that my hardisk turned into 2GB!!,when i’m booting my PC,it’s giving me the option that if i want WINDOWS2000,or WINDOWS ME,and i made SCANDISK,there was no bad sectors at all,so what are the possible reasons for this,and how to repare it?