3. Seriously! I even got old 1.6er vanilla jars sitting around.
4. There's a tool called MCNostalgia, capable of reverting jars back to older dates.
5. Minecraft Version Changer: http://www.minecraftforum.net/…r-109-really-easy-to-use/
This is the simplest way, how to you downgrade minecraft if you don't have backup.