I had a orginal windows xp home with product key but i had installed xp professional pirted edition can i convert it into xp home orginal?

No sir you can just convert your windows into xp home original.you will have to format the pirated windows which you have then re-install your new xp home into it
use your xp home cd to format your hard disk by booting your system with the xp cd and then install your windows
Feel free to ask anything
Thanks