Quote from Tintedwreck
Hit the start menu, go to Run then type this: %appdata%. This will then bring you to a folder where you should see .Minecraft folder. Double click it and you should see all the files involved with minecraft.
If you have done this then search every folder and if you still haven't found it, make a backup of your saves file and delete .Minecraft. That forces minecraft to make a new folder with all new files. If this doesn't work at all your doing something wrong.
Also there are multiple tutorials on Youtube about this issue.
Pretty sure that the .bin installation has been changed and you install stuff into the versions folder along with renaming them...