Thanks for your response cereal, inside the config file it says "color_scheme= ", so this probably means that I have to set the color scheme back to default. I don't think I ever changed the color preferences before, so I don't know how this could of happened all of a sudden.
I tried modifying the .config file "color_scheme=default" but it didn't work.
I tried "color_scheme=Default" but it didn't work.
As I was doing this I made sure Geany was closed and I saved the .config file.
I tried re-installing Geany from Synaptic Package Manager but it didn't work.
Yup, check if in ~/.config/geany/colorschemes/ there are files and set one of those as default, for example: color_scheme=github.conf, include the extension, if there aren't any files then you have two choices:
reinstall Geany, so uninstall the programm and delete the configuration folder under your profile, i.e. ~/.config/geany/, not the .config directory itself, because it contains other software data;
download some themes and save them to the colorschemes directory and edit geany.conf.
Note: I'm suggesting to edit geany.conf because the switcher interface doesn't work properly. Hope it helps, bye!
You know what? I got it. It had nothing to do with the color scheme. It was to do with the amount of colors the screen was displaying. When the screen was set to 16 colors, it displayed a blue background for some reason. But when I switched it back to true colors, the background became white again.