I did the Census online, but lost my comfirmation number. What do I do?

Answer 1

Live your life.  The chances of anyone asking for it is pretty slim.

Answer 2

Do nothing. They give you a confirmation in case you need to prove that you took the census. It’s not mandatory to take the census. 

Answer 3

There’s no law mandating completion of the US census survey. So you don’t need to worry about your confirmation number.

Answer 4

Nothing they won't ask for it. You did your duty.