This is quite a common problem with the temporary note getting stuck off screen! If you want to get it back you can do the following steps:
This should be your note returned, if not then let me know and we'll see what else we can do
Hi Stuart...unfortunately when I right click over the yellow post-it nothing comes up. Also tried it with 'Temporary Notes' in the drop down menu at the top.
Can you confirm you are trying to right click on the Temporary Note from the task bar along the bottom of your PC?
Should look something like this (may vary depending on your operating system)