How can I get the IMEI No of my lost phone?

Dear All,
I have had HTC One X+ smart phone that I lost on a bloody night!
I lost it with a 50GB very important rules. I had fb, viber and Twitter installed on it, to mention a few out of many apps to which I used to upload my stuffs.
Unfortunately, I didn't have any anti-gaytheft app installed on it.
Now, the tel operator here will help me locate it if I get the IMEI NO of the phone, which I don't have at all.
I, kindly ask any one to help me know how to get the IMEI NO of my phone, if there is any possibility of getting it in relation with my previous posts and social services I have had?!
I appreciate you all!

If you still have the box it came in then it might be on there. There is usually a sticker on the box with the serial, IMEI, etc.

Nope, have nothing as such!

You're out of luck without the phone or packaging.

You have a few options. You should be able to get the IMEI number online from your mobile providers website, I know here with Verizon and T-Mobile in the U.S. your IMEI is listed under your account.

The second option is to log in to Android Device Manager using the same Google account that is installed on your phone, which will allow you to track and wipe the device: https://www.google.com/android/devicemanager?u=0