THUNDERSTORMS AND LIGHTNING IN THE VICINITY OF THE ARPT PREVENTED ADDING FUEL TO THE ACFT AND RESULTED IN A DELAYED DEPARTURE. THE LOU VOR WAS OUT OF SERVICE, AND THE FLT WAS RADAR VECTORED UNTIL IT WAS CLEARED DIRECT TO LEX AND FOR THE APCH. AT THE TIME OF THE CLEARANCE THE FLT WAS 25 NM WNW OF THE DEST ARPT AND NORTH OF THE FLT PLAN ROUTE. BOTH APCH CONTROL AND TWR WERE CLOSED FOR THE NIGHT AT LEX. THE VOR AND ILS AT THE DEST ARPT WERE REPORTED TO BE OPERATIONAL. ANOTHER COMPANY AIRCRAFT LANDED AT LEX WHILE THIS FLT WAS EN ROUTE. ATC ATTEMPTED TO CONTACT THIS ACFT WHEN IT WAS OBSERVED ON RADAR TO BE DESCENDING FROM THE ASSIGNED ALT PRIOR TO REACHING THEIR DEST. ATC REQUESTED THE ASSISTANCE OF ANOTHER ACFT'S CREW IN ATTEMPTING TO CONTACT THIS FLT BUT WERE UNSUCCESSFUL. SHORTLY AFTER RECEIVING APCH CLEARANCE, THE CREW SPOTTED AN ARPT WITH RUNWAY LIGHTS ON, ENTERED THE TRAFFIC PATTERN AND LANDED. THEY WERE SEVENTEEN NM FROM THEIR SCHEDULED DEST.