I’ve put together this graph and I would like to be able to add a legend to it but can’t seem to figure out why it’s not showing up and how to easily add it.

I have the following graph.

I have a data set with a big negative value, so I used gg.gap package to make a discontinuous y-axis. The code worked well but after adding the function gg.gap the legend was deleted.
I tried adding a legend using the add.legend argument but it didn’t work.
Am I doing something wrong?
Here is a sample code

Is there a way to change the orientation of the items in the legend of ggplot2 chart?

I have a problem making the plot legend to show. I’ve checked other posts and most of them mention that color should be defined within the aes() of the ggplot.

With the following data, I am trying to create a plot as shown, but the order of legends as: mgCST Group, CST Group, Treatment Status. However, ggplot is ignoring all attempts to order the legends