Hi there!!
Basically this happens due to dbus errors and it's too simple to fix it...

Here are the commands that i used to fix it..

1: xfce4-panel --quit

2. ps -aux | grep xfc

3. pkill xfconfd

4. rm -rf ~/.config/xfce4/panel

5. cd .config/xfce4/

6. ls

7. rm -rf panel

8.cd

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

10. xfce4-panel
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Subscribe fast !!