I lost the link to edit my plugin. I have gone in circles trying to edit my plugin's files. I can't get back to the page where the file are on the left, and edit links are on the right.

In the admin.cgi, i can't get there from "plugins" link on top bar, that only allows me to .... not actually edit files contained in plugin.

Where do I have to go to display the page from which I can edit my files?

You can only edit the files of plugins that you haven't installed yet. So you either need to uninstall your plugin, OR copy the plugin.tar file from the Installed directory to the Uninstalled directory.