It sounds as though you are planning to make an entirely new account, as any avatar you have for your original account will automatically have all of your inventory, your friends lists, etc. Many people have numerous avatars for the same account, and use the different avatars for different things. As another person said, there is no reason to create an entirely new account because of a messed up avatar. You should actually be able to go back to the original shape of the avatar in many cases and start over. But at the very least, you can find either freebie modifyable shapes out there, or buy very nice shapes and skins for your avi.