Xfce4 panel is broken, how to restore it to the default panel without exiting current desktop？

Issue:

Xfce4 panel is broken.

if you selected the 'One empyt panel' option, then your desktop will look like below,

open a terminal, then minimize the terminal, and it is gone nowhere,

So, how to restore xfce4-panel to the default?

1. bakcup your xfce4 config

cp -r ~/.config/xfce4 ~/.config/xfce4_bak

2. kill Xfce configuration daemon,

pkill xfconfd

3. delete existing config,

rm -rf ~/.config/xfce4/xfconf/xfce-perchannel-xml/xfce4-panel.xml

4. restart xfce4-panel

nohup xfce4-panel -r &

5. then select 'Use default config'

Done.