Don't know what happened. Branches are growing up and the tree now has cherries.
Weeping Cherry Tree Has Branches Growing Up and It Now Has Cherries
Your weeping cherry was probably grafted onto a stronger rootstock. This is what is producing the upright branches, and also the cherries. It's possible that cold weather damaged the more delicate weeping cherry. You can prune out the fruiting branches, as explained in this article: https://www.gardeningknowhow.com/ornamental/trees/weeping-cherry/pruning-weeping-cherry.htm
Hopefully, some of the weeping cherry is still viable.