I selected a command to paste on the notepad on the left, but instead of copying I accidentally pasted an old command. Now I don’t know what was written there, and I cannot seem to reload the original values. Restarting the Kernel does nothing.
You can go back by using the “Undo” keyboard shortcut, for example Ctrl + Z on Windows and Command-Z on Mac.
If this does not work, the ultimate workaround is that you close your browser and come back in 20 or more minutes. By that time, you will get a new VM with a brand new notebook.
If you have already left for some time, the note will be correct by the time you resume.