i had to go into my files and find the haven file to delete the full screen folder for it to go back to normal. (not sure correct terms, hope this helps)

I clicked full screen option and now my PC just a white page - I have to shut down PC to get rid of it and although I unsubscribed to Ender mod and then resubscribed - when I go to use Ender client I am straight into the white screen. Unsure how to change this as I could not see any obvious files to change