Hi Rosss.
Since your panel is gone I'm assuming you have nothing to click on so let's start by open a terminal with the keyboard.
To open the terminal with the keyboard use this key combination
ctrl+alt+t
Next, let's open the settings manager. To open the xfce settings manager type this in the terminal and press enter
xfce4-settings-manager
In the settings manager click on the panel icon and this will open the panel window. From here you can edit existing or create new panels.
Here's a video that explains how to create and customize panels
Linux Lite Learning ::: Whisker Menu, Panels & DIY Dock!