You need to contact your Uber driver and or Uber for help on getting lost item as hopefully the driver kept lost item safe and was not taken by a fare after you.

https://help.uber.com/riders/article/contact-driver-about-a-lost-item?nodeId=53539bde-f6f4-4909-85de-fa0b99f82be0

Hopefully your phone is locked, either by a PIN, fingerprint, or facial recognition. If you think it might not be locked, you can change your Google account password (the one you use for that device) and that may help limit what the "finder" can do with it. I think you also can remotely "wipe" it, but that would be pretty drastic at this stage.

How do I contact the driver about the lost phone?

Did you look at the article I linked to ?

I have no way to contact the driver. How can I find him?

You should contact Uber directly.

If you booked the ride through your account, you may still have some driver information.

If you rode on someone else's booking, ask them who the driver was.

That's the problem- can't speak or find a 'person' at uber.

Hi 8142933022, did you already try the method described in the article linked in the first reply:

https://help.uber.com/riders/article/contact-driver-about-a-lost-item?nodeId=53539bde-f6f4-4909-85de-fa0b99f82be0