How to undo my instrument delete?

Hi,
I am new to cubase and wonder if I could undo my intrument delete?
Lets say, I accidently click ‘no instrument’ button in inspector but when I undo, it does not bring it back. Is there any way to do so?

Thanks!

You could use File/Revert to get back to the last saved version of the Project. But there is no undo for it.