How to restore lost emails from my iCloud account?

Good afternoon,

I urgently need your help, 

10 days ago all Mail for ******@icloud.com  disappeared; for a year; I lost a lot of important information, did not take any action to delete it from the mailbox, the correspondence just disappeared for a year (please help me restore it, this very important, thank you for your help and waiting for your answers

[Edited by Moderator]