How to retrieve lost contacts from my iPhone

I synced my iPhone with my Mac, but it seems only to have kept all the calendar and contacts information that was on my Mac.

I have therefore lost all of my contacts from my iPhone which I need for work.

I have tried everything in restoring from iCloud.com and from back up, but the latest iPhone back up on the cloud was after I had done the sync with my Mac.

Can anyone help please as I am lost without my Contacts.

thank you

[Re-Titled by Moderator]