Hi I'm new to these boards so I'm hoping that someone out there can help me.

I have a very large and extended Virginia creeper which was beautiful untill 3 days ago when the top half of it turned brown and it looks like its dying off. I haven't changed the way its looked after, I'm not a brilliant gardner so have pretty much left it alone so this was a real surprise to find that it appears to be dying. The bottom half is still very green and bushy so should I cut it back to where the green is or just leave alone and keep my fingers crossed ? any advice would be greatly appreciated.