It would be great if zynga can implement hotkeys for your avatars just like in Sims,but I doubt if this can be done in flash games since the game is only controlled by a mouse. This makes stuff simple but it makes problems like this more annoying.
Now there is such a way wherein you can locate your child (or any lost avatar for that matter). This technique involves several steps and I will show a step-by-step guide with pictures and captions below:
1. Now if you refer at the picture above, I have set up the typical scenario. The child is in there hidden behind some objects. Now you will definitely panic if you encounter this for the first time.
2. Open the MY STUFF window. This is the lower right icon on your dashboard. Opening this will bring you this window. Now go and select on FAMILY ALBUM.
3. Now go to the picture of the avatar that is missing in action. In this case our little boy. Now go and click on customize.
4. This will bring you to the avatar customization screen. Now skip the customization unless you want to change his looks and just click on PLAY. This will in turn switch the control to your child in-game.
5. Click on a visible space on the ground and junior will move to that area. Apparently he was taking a nap behind the peach trees on this one.
I hope this Frontierville Guide is of help especially to those who have lost their child or spouse. Hopefully, Zynga could resolve this issue so that we will not lose track of our loved ones again.