iPhone 6s will not synce with iTunes

For some reason, my iPhone 6s will not sync with the iTunes on my computer. It did before, but will not now.

When I connect the 6s to the laptop, which has Windows 10, it takes forever to bring up iTunes. Then the iTunes is frozen unless I disconnect the iPhone. I've looked over the 6s and can't find anything out of the ordinary and I've even reset it. I'm out of ideas.