Numbers spreadsheet missing

If your documents were saved in iCloud then be sure that your device is signed in to the account you were using before and make sure Numbers is set to use iCloud Drive.

Settings > Your name > iCloud Drive turned on and Numbers is turned on below that.

Settings > Numbers > Document Storage set to iCloud Drive.

SG

I have the same thing happen to me but on my iPhone. My numbers spreadsheet disappeared not only on the phone but on the cloud as well. Tried restore but it said there was nothing to restore, and I know it was on the cloud because I had viewed it from the cloud a week ago.