Ax_Why I'm network icon vanish

x_a show NIC(network interface card/adapter) status

$ ifconfig -a

x_b modify configuration file change addition eth0 or your NIC

$ vim /etc/network/interfaces

x_c restart networking service

$ /etc/init.d/networking restart
ok, already resolve network connection problem.
But.
Don't have network icon

Bx_Resolve

x_a stop network manager service

$ service network-manager stop
$ service NetworkManager stop // kali 2020.1 new service name

x_b delete networkmanager.state

$ rm /var/lib/NetworkManager/NetworkManager.state

x_c start network manager service

$ service network-manager start
$ service NetworkManager start // kali 2020.1

x_d modify configuration file change false to true

$ vim /etc/NetworkManager/NetworkManager.conf

Successfully!