To every host and hostess disaster comes one day.

"Last week we were making Oeufs a la neige and someone handed the cook salt instead of sugar. They were pretty to look at but terrible to taste. . . ."

"I walked into the living room and the dog was standing next to the coffee table with a pound of pate in her mouth. . . ."

"It was our first post in Vienna and we were giving a dinner. A visiting minister from Sweden was coming and right before dinner the electricity went out. . . ."

"Our bird flew into the lemon meringue pie. . . ."

The Oeufs a la neigh went into the trash, the pate went into the dog and no one had lemon meringue pie for dessert that night. Knowing when to cut your losses is part of entertaining.

But not everything that goes wrong has to stay wrong.

The Countess, Ulla Wachtmeister, wife of Sweden's ambassador to the United States and noted for her creative entertaining, coped with her Vienna blackout by making dinner on a small, picinic kerosene stove: "It took four hours instead of a few minutes."

Another hostess left in the dark built a fire in the fireplace, covered baking potatoes with hot coals and served them to her guests in front of the fire with lots of butter, chunks of cheese and black pepper.

In addition to blackouts and animals gone bereserk, there are late guests and extra guests and too much salt and not enough and it's a wonder we bother at all.

For extra guests there is the extra plate and dividing six chocolate mousses into seven dishes or announcing you're on a diet and never, no never eat chocolate mousse. Always serving soup or stew takes care of the problem of the late guests, but, still, even the hostess who knows better will give into the occasional roast or leg of lamb. To keep it from overcooking, take it out, cover it to keep the moisture in and put it back to finish cooking when the doorbell finally rings.

When it is all too late, Donald Miller of the Academie de Cuisine in Bethesda suggests, "If the meat is too tough or overdone, slice it thin and serve it with a sauce." Slicing it thin is also his advice for the homemade loaf of bread that rises in lumps or lists to the right and looks nothing like the pictures in magazines.

If you've read two tablespoons salt for two teaspoons, you may simply have to triple the recipe. Or, if possible, serve the dish cold instead of hot. Cold cuts the taste of salt.

More common, says Miller, is the dish that hasn't been salted enough. "A student brought in a sauce that tasted terrible, but when it was reduced to strenthen the flavor and salt was added, it was wonderful."

Some sauces, like some people, respond to a jolt of brandy or sherry.Having saved the sauce, pour it over your other mistakes. Everything, that is, save the dish that burns. Throw that away and make omelettes instead.

Easiest to cope with is the failed dessert.

"Architects grow vines to cover their mistakes," says Miller. "Pastry chefs use whipped cream."

The best way to cope with anything from blackout to burnout is, says one Washington party-giver: "First, remember it happens to all of us and second, always have plenty of wine."