I believe everyone else is correct. One 110 leg of the 220 system is out. Any high winds or heavy snow in your neighborhood recently? Can you see any problems with the three wires coming in to your meter box? Wet your fingers and touch each wire to see if it is hot. (JUST KIDDING!)
On one of my rental properties, there is a big box with two huge fuses inside, one for each leg. Perhaps you have something like this and one has failed.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13