I lost my iphone in my house and battery is dead. How do I go about loacting it?

If it's dead, the the only thing you can do, is to look for it the old fashioned way.

There is no way to find a dead iPhone any other way.

Find My iPhone will not work if the iPhone is dead, and you won't be able to make it play a sound if its dead.

is the iPhone turned off?

If you lose your device and you think it is nearby, you can use Find My iPhone on iCloud.com to play a sound on it to help you find it. The sound plays even if the device is in silent mode or the volume is muted.

If it is in the house and turned off, then locate it as you would locate any other item in the house.