Minecraft Crashes after clicking a world?

After I click a world in Minecraft (1.7.9) it closes into the Minecraft launcher… It doesn't even have a crash report. And I can't copty+paste anything into the files because I saved it into my desktop and there's no file for minecraft that has the Minecraft.exe inside of it… I looked and it's just on my desktop.

On windows vista/7 you need to click on the start menu and search %appdata%. On Xp you need to use the "run" option and search for the same. Once you've done that, open the folder that says "Roaming". There you will see a Minecraft folder. Open it. Copy and paste the files into the appropriate folders from your desktop.

If Minecraft still crashes, try uninstalling Java7 and install Java6 from Oracle's website.