i lost my htc sensation mobile 2 days back how can i find it

Even with the IMEI number you can't trace it. The police could if it was stolen by like gunpoint or during a felony or something, but a lost phone, they won't get a warrant to get the carrier to trace it.

If it's an android phone and you enabled the android device manager, you could have tracked it while it still had battery life, but after 2 days, the battery would be dead. If someone found it, they more than likely wiped it and I believe that stops the android device manager from tracking it anymore once someone else signs in with their gmail.