I wanted to use a mod, Optifine, but I'm pretty sure my brother gave me the wrong steps because after he said I did it right, after I pressed login, it had the mojang logo, then the window showed the dirt blocks and it crashed. So I watched a couple YouTube videos and I ended up having a .minecraft folder with only the bin and a "version" file. And I want to know if there's any way to have a fresh, new .minecraft folder. And if so, can you state the solution below?
You will be able to obtain a fresh new .minecraft folder by deleting it and Force-Updating upon launching Minecraft. If you don't know how, open up Minecraft, hit Options, hit Force-Update, and hit Play!
Are you playing using the browser? If so, download the Minecraft.exe and use it.
Try troubleshooting on the Mojang website depending on what comes before Not Downloaded using this link: http://help.mojang.com/customer/portal/articles/1003067-error-not-downloaded