Was that one stem brown or Black?..Brown means it was just broken or bent somewhere..Black is wilt..if all the way..then prune that one stem even with the soil..if brown to just a certain part of it..then prune right above the leaf axil where there is some green...Jeanne

Harry:
I thought my Betty Corning had wilt but I found I broke off a stem which is what caused it to look like wilt.
Good luck!

Yep broken stems caused by critters and other factors can cause stems to wilt. Nothing to do but prune it back to where it is not wilted or to the ground if the entire stem is wilted.

I pruned the wilted VV vine back to the ground last night. I laid on the ground to get a close look at the base of the plant. My only guess was maybe the base rotted due to a lot of rain and mulch built up against the vine. The vine seemed intact. I moved the mulch away. Hopefully the remaining vines will continue.

Give it time Harry and I am sure it will return if it was just a case of damaged or rotted stems.

Harry..good lesson hon..that is why I always say to pull the mulch away so it doesn't touch the vine..the mulch retains moisture and can cause stem rot...Jeanne

Here is a link that might be useful: Stem Rot