I have my IMEI number how can I find my lost iphone

IMEI no. may not help you to track your device.

Did you enable Find My?

If you didn't turn on Find My [device] before your device was lost or stolen, it can't be used to locate your device. Change your Apple ID password. Change the passwords for other internet accounts on your device. This can include email accounts, Facebook, or Twitter etc...

Know more here --> If your iPhone, iPad, or iPod touch is lost or stolen - Apple ...

Don'ts

If you remove the device from your account after you erase it, Activation Lock will be turned off. This allows another person to turn on and use your device.

I lost my iPhone