I have lost my mobile

If you lost your cell phone then you nee to make a police report that it's lost so that you have a record of that and then you need to contact your cell phone provider to see if they can help you recover the phone by tracking it. If they can't track it then you should have them disable the sim card so no charges will be associated twith your account.
There is a place on the web that you can go and register your phone and maybe it will turn up there.

http://www.3gadget.com/frmchkYourGadget.aspx