We get dozens of mails every week asking us the process to locate a device by just the phone number or the IMEI number. To tell you the truth:
We cannot locate a phone just with Phone number or IMEI number
We require an input of cell tower information (the unique id of the cell towers scanned by the device). This is usually MCC-MNC-LAC-CID. You can get this from your device in a number of ways. The easiest one, is to use an android app (like these) which scans the cell towers around the device and shows you this information.
If your phone is lost and you do not have direct access to get this cell tower information - we cannot help you locate that device. Please contact law enforcement. (or try using Google's find-my-device option)