AFTER MAKING AN INSTRUMENT ACPH TO LACONIA, NH, THE PLT LANDED, PHONED HIS WIFE & ADVISED HER OF HIS INTENTION TO FLY TO MOULTONBORO, NH. AFTER TAKING OFF, HE ADVISED MOULTONBORO UNICOM THAT HE HAD DEPARTED LACONIA & WAS OVER A NEARBY LAKE, BUT WAS HAVING A PROBLEM FINDING THE ARPT. THE UNICOM OPERATOR ADVISED THAT THE WX WAS BAD, THERE WAS FOG AT TREETOP LEVEL, BUT IF DESIRED THE RWY LIGHTS WOULD BE ILLUMINATED. THE PLT RESPONDED THAT WOULD NOT BE NECESSARY, HE WOULD CIRCLE A COUPLE OF TIMES TO SEE IF HE COULD FIND THE ARPT, IF NOT, HE WOULD RETURN TO LACONIA. NO FURTHER TRANSMISSIONS WERE RECEIVED FROM THE ACFT. WHEN THE ACFT DID NOT ARRIVE AT EITHER DESTINATION, A SEARCH WAS INITIATED. IT WAS FOUND ABOUT 50 FT BELOW THE TOP OF A MOUNTAIN RIDGE WHERE IT CRASHED AT AN ELEVATION OF APRX 2000 FT. NO EVIDENCE OF A PREIMPACT/MECHANICAL MALFUNCTION OR FAILURE WAS FOUND.