All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad, sallallaahu 'alayhi wa sallam, is His slave and Messenger.
There is nothing wrong in supplicating Allah Almighty to make your ex-husband (who divorced you) marry you again.
There is also no objection if you ask someone to talk to him on this matter or for you to talk to him yourself if you need to do so.
Allah knows best.