Q.weeping cherry tree
I have 2 weeping cherry trees , one is doing good the other the top 1/3 seems to be dying can I cut it down and if I do what do I do with the top can I cover it somehow to encourage grown. I have fertilized it and the limbs are growing out of the 2/3 lower trunk but nothing up top.

Unfortunately it sounds as if the one Weeping Cherry top graft has died. Weeping Cherry Trees are grafted onto the trunk of a different root stock. The growth that you describe is growing from the root stock--not from the Weeping portion of the tree.
If this is a new planting--perhaps you planted it last season--the garden center or greenhouse may offer a replacement.
Here are some articles about care information.
https://www.gardeningknowhow.com/ornamental/trees/weeping-cherry/weeping-cherry-growing-tips.htm
https://www.gardeningknowhow.com/ornamental/trees/weeping-cherry/pruning-weeping-cherry.htm