Q.Crape myrtle
My lavender and white crape myrtle only are coming back from roots and not the branches like the other crape myrtle that I have please help

It is possible that the primary stem and foliar crown has died back for some reason, water deficit (drought stress) is very common. But the lower trunk and root system is still viable and putting up suckers. If you select one sucker, in the highest position on the stem, to grow up and become the primary tree trunk, it may or may not develop as the same cultivar with flowering characteristics as the parent tree. You can water, wait and see, or replace with a new tree.