Lost my I phone

If you are saying that the Find My option on the phone was not enabled, you will have to look for the phone the old fashioned way. Check restaurants, stores, etc that may have visited recently.

Follow as many of the steps as you can in this Apple Support document:

If your iPhone, iPad, or iPod touch is lost or stolen - Apple Support

If Find My has been turned OFF or was never ON, then you are not going to be able to locate your lost device electronically. You will have to attempt to find that device the old fashioned way and that is to physically look for it by back tracing your steps.

Axel F.