Q: why  i cant bakup my iphone 6 using my laptop with windows 8

Hello talaluae,

After reviewing your post, it sounds like you can't backup to iTunes. I would recommend that you read this article, it may be able to help the issue.

If you can't back up or restore your iPhone, iPad, or iPod using iTunes - Apple Support

Thanks for using Apple Support Communities.

Have a nice day,

Mario