My contacts are no longer on my watch. How do I get them back?

Do you have all your devices set to use the same account for contacts? Get help using iCloud Contacts, Calendars, or Reminders - Apple Support

On the phone make sure that when you go to settings>contacts - the default account is set to the one you want and when you go to the watch app that the watch is set to mirror the phone. I use iCloud as the default account and everything stays synced much better between all my devices.

My watch series 4 does not mirror my iPhone. I do not have any favorites or contacts... this happens a lot I do not know how to get my contacts back. Can someone help me please???

Did you go to that link? You need to create your own thread.