My husband and I saw a wonderful black and white film late night on our local public TV station about 1981 that looked to be shot 1950's in France. Plot: A man was going to wine cellar when an explosion - probably Allied air cover for beachhead invasion - buried the door shut. He survived a year(?) with wine, cheese, candles. Candles ran out, then movie in dark for awhile, just his voice recounting his thoughts, memories, wondering how the war was going, who was winning... He was finally dug out during reconstruction efforts. WE THINK. We want to see the film again but have never been able to learn the title.

Possibly this? (Doesn't match exactly your description, but worth a shot... )
The Blockhouse (1973) - IMDb (http://www.imdb.com/title/tt0069803/)
http://www.nytimes.com/1981/06/12/movies/sellers-and-aznavour-as-world-war-ii-prisoners.html

Also, check your PBS station's online schedule. Our station's schedule is monthly and shows past and future programming..

Possibly this? (Doesn't match exactly your description, but worth a shot...)
The Blockhouse (1973) - IMDb (http://www.imdb.com/title/tt0069803/)
SELLERS AND AZNAVOUR AS WORLD WAR II PRISONERS - NYTimes.com (http://www.nytimes.com/1981/06/12/movies/sellers-and-aznavour-as-world-war-ii-prisoners.html)

Not the same one, but SO close to the plot! We're huge Sellers fans too. His Undercovers Hero shot in WWII Paris where he plays 6 roles is amazing - and not on his filmographies.

Also, check your PBS station's online schedule. Our station's schedule is monthly and shows past and future programming..

Gosh, I tried a few years ago, but since this was on a late night 1980's schedule they couldn't find it any longer. :-(