I installed kali linux with the dual boot on ubuntu 16.04
It is not a question about Kail linux, it is a question about recovering Ubuntu
I agree we do not support Kali
I agree the op should have made backup
We do, however, support Ubuntu data recovery after I stalling other os windows specifically
Recover Windows 7 boot after installing Ubuntu 14.04
recovering lost data after installing ubuntu on windows 10 using testdisk
So I believe we should help in this case as well