With the following script you can easily backup your .minecraft folder.

Just copy this text into your Batch-File:
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robocopy C:Users"Your Username"AppDataRoaming.minecraft "C:"the path of the folder where you want the backup to be saved".minecraft" /MIR
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For Example:
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robocopy "C:UsersChuckNorrisAppDataRoaming.minecraft" "C:UsersChuckNorrisDesktopminecraft backup.minecraft" /MIR
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The Batch file simply mirrors your .minecraft folder to the direction you chose.
Keep in mind that all files in the backup- folder, which are not in the source-
folder will be deleted! So you shouldn't save any new files in the .minecraft backup-folder.

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For all those who don't know how to create a Batch-File:
1. Create a new text- document with the Editor
2. Open it
3. Copy the text above, paste it into the text- document and edit it so that it fits to your paths and username
4. Go to "File" -> "Save as"
5. Select "All Files" at File Type
6. enter a name with the ending ".bat" . This is really important. If you don't do that it won't be a Batch- File
7. To use the Batch- File just doubleklick it like an exe- File

I'm sorry for translation mistakes. Pls point them out to me if you find one.
But i hope i could help some of you :)