Can I locate my iPhone with my IMEI number?

As an individual, you can not track an iPhone (Any Phone for that matter) using an IMEI number.

Find My iPhone / "Find My" can be turned off only if...

1. You have shared your Apple ID & password with someone
2. You have removed 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. If you're using iCloud and Find My [device] on the device, sign in to iCloud.com/find or the Find My app on another device, select the device, and click Erase. After the device has been erased, click Remove from Account. This will turn off Find My.

The only way the person could turn off Find My is if they knew your Apple ID and password. Did you respond to a phishing message from “Apple” saying your phone had been found, and to log in using a link in the message? If you did that all information in your iCloud is now in the hands of the criminal who sent that message. So the first step is to change your Apple ID password, and after that review the personal information that is now in the hands of the criminal.

 lost my iPhone .but i just realized the person has turn off find my iphone can i get back my iphone . I can locate my phone with the imei number

Please help me locate my phone please

how to change pw . I have samsung phone

Log in to https://appleid.apple.com, where you can change your password.