forgot my numbers password

if you assigned a password to a document in Numbers to password protect the file we cannot really help you. You look through Time MAchines backups for versions in the past before you protected the document. you may have also shared an unprotected version of the file with someone using email of a removable drive.

If you mean you located a document on iCloud and you do not remember your login, then you shoudl recall that you login using an Apple ID, and that you can set the password by visiting this link:

https://support.apple.com/en-us/HT201487