how do you un-do?

Can you give us more information on your question  " how do you un-do?", so that we can assist you further.

Thank you.

I apologize in being premature with my question.  I figured it out myself.

I had a long list of items that we are selling.  I meant to delete a single item and deleted them all -- potentially hours of work to recreate....  but I was able to "undo"  my deletion.

Thank you.