how do i get my itunes to open?

i updated my itunes to itunes 8 and after that i can no longer get into itunes. it just won't open so i uninstalled then reinstalled it didn't work. so i installed an older version and a message would pop up saying the file itunes library.itl cannot be read because it was created by a newer version of itunes. so i trashed that file and itunes still wont open now theres no message its just back to not opening and at one point something said that my audio configuration wasn't right. i have repaired itunes and quicktime and still itunes won't open.what can i do to get itunes to open?