Apple Watch is not syncing
What is the cause of apple watch not syncing? How do you fix it? Tried pairing with camera and manually.
There could potentially be many reasons. What series watch is it? What watchOS version is currently on it? What model iPhone? What iOS version is on it? When you try to pair them do get any error messages our other indications? Without knowing anything else, maybe one off these articles will help:
If you see 'Unable to Verify Update' when updating Apple Watch - Apple Support
If you don’t have enough space to update your Apple Watch - Apple Support
If the update fails, see fireyjack's reply to:
apple watch 3 series won't update , w… - Apple Community
I was given a 7000 series Apple Watch - Apple Community