Q: grey vertical lines have appeared that cover most of my screen on iPhone 6

Hello redjonty,

Thanks for using Apple Support Communities.

I see from your post that you're seeing lines running across the screen on your iPhone.  I know this must be an unsettling issue, so in order to get this resolved I suggest going through the steps below.

If you see lines, missing sections, discoloration, or poor image quality

1. Try to restart your device. If you can't restart, force restart your device.
2. If this doesn't work, restore your device.
3. If you still see the issue after you restore, contact Apple Support.

Get help with the screen on your iPhone, iPad, or iPod touch - Apple Support

Take care.