I lost my iphone 6s but I m unable to locate it can u please suggest any idea

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. However you may Change your Apple ID password. Change the passwords for other internet accounts on your device. This can include email accounts, Facebook, or Twitter etc...

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.