hmm... if they're still on the map and turned on, you should be able to see through their camera in the camera tab
it's a start to figuring it out, that's an expensive loss...
Viewing post in My Omega Kerfur went missing instantly
also they *can* explode when damaged, but you can find and gather all their parts to rebuild them- if you find a part.... well.... time to get hunting :P
oh, also, if you can see through their camera, you can also take control of them with the weird green hurricane lookin button and using the control sliders, might be able to dislodge them manually
check the rivers and low areas, most parts are round enough to have rolled to the lowest points possible
worst comes to worst, you can make another, but it will require either fetching a core from another save, or going into the cave...
If you choose the legitimate way, bring supplies, and you can wear more than one backpack, but I don't recommend trying to stay awake or leaving to sleep, better to rest when you can in there, it's a journey.