How can I find the last active location of my stolen iPhone 14?

The location shown in Find My is the only location available. There are a number of reasons why it might not be further updated or no longer showing, but in any case there's nothing you or Apple can do to about the problem (and we're all just fellow users here; Apple Support does not participate in these forums). If you've put it in Lost mode, that's all you can do. You'll just have to hope that eventually a new location appears that you can report to the police.

As to what happens when you put your iPhone into Lost Mode, see:

Use Lost Mode in Find Devices on iCloud.com - Apple Support

Regards.

What is the message that appears on your phone when you open Find My?

"No Device Found"? Find My has been turned off.

"Offline"? One or more of the following are true:

• The battery has run down
• The phone was powered off
• The phone does not have an Internet connection where it is located

In this case, the Last Known Location will only be displayed for a day and will not be displayed again until Find My is able to connect to your phone.

Apple does not know your current location. You will have to keep trying a few times each day to see if the location of the phone will appear again.

Since the phone was stolen, there is almost zero chance that you will be able to recover the device, so it makes sense to erase the phone as an extra precaution.

Even if your phone might appear again......what would you do? Certainly you would never want to try to recover the phone yourself. People have been killed trying to do this.

Watch out for any messages that you receive that indicate that your phone has been found and you just need to provide more details.....like your passcode, Apple ID and Password......so the phone can be returned to you. Messages like this are scams from the thief who is trying to get into your phone.

Apple will never contact you to let you know that your phone has been found. The notice you received was a fake, trying to get you to remove the iPhone from Find My so Activation Lock is removed, freeing the thieves to use or resell the phone, or otherwise get you to give them personal information.

The police cannot track your phone via the IMEI. The only entity that can do anything with that information is your cell carrier, and all they can do is blacklist the phone. They cannot track it.

Regards.

Recently i got a mail from apple itself that my iphone has been found

Apple will never send a message like this. The email was a scam that was trying to get you to reveal your Apple ID, Password, etc,.....as we noted and warned you in our first response to you.

Hopefully, you did not provide any information to the criminals who have your phone.

I’m thinking of getting the phone tracked through the police using the imei id

The iPhone cannot be tracked by the police using the IMEI. Your carrier might be able to track the phone, but they will usually only do this in cases of missing persons.

It will not hurt to ask your carrier to try to track the phone, but I would be very surprised if they will help you.