Have you ever had the trouble of when you install mods, then you update minecraft and try to install mods, it crashes? Well this is how you can fix it.
Step 1: Cleansing your Minecraft
Ok the first step is to press the "start" button and "R" at the same time which should bring up "run".
If that doesn't work then go to "start", "Accessories" and then click "run".
When the "run" program pops up then type "%appdata%
Next step is to copy your ".minecraft" and paste it where ever you want just in case something wrong happens but i have done this 3 times and nothing bad has happened. Then after you have done that your next step is to delete your ".minecraft" and run the launcher which should update and give you a completely new .minecraft folder.