Q: Can't locate my phone

Did you have the find my device switch enabled in your iCloud Account's settings on the device?

If you did, there are a number of reasons it may not be found.  It must be powered on and connected to a data network (cellular or wif) for it and Apple's Servers to communicate. If the battery has run down, or if someone has simply turned it off, it will not be found.  If someone has restored it as new, then your iCloud account and its settings have been wiped from the device, and it will not be found.

If it cannot be found, then there really is nothing you or anyone else can do, sorry.