Lost your phone and do not have any tracking software installed on it (ie Lookout, Seekdroid, etc)?
1. Install Plan B to the phone that you are trying to find from the Android Market website: https://market.android.com/details?id=com.lookout.labs.planb
2. Plan B will start automatically and send your phone’s location to your Gmail address.
3. If it doesn’t start, borrow a friend’s phone and text the word “locate” to your lost phone.