Jean Hilliard was literally frozen stiff, ''like a piece of meat out of a deep freeze,'' when a friend found her in the snow after a night of 22-below-zero temperatures. But the 19-year-old has made an unusual recovery.

''At worst, I might lose a couple of toes,'' she says. ''I can't explain why she's alive,'' Dr. George Sather, who helped treat the young woman, said today. ''She was frozen stiff, literally. It's a miracle.''

Miss Hilliard was frozen after a midnight automobile accident in rural northwestern Minnesota. When she arrived at the Fosston, Minn., hospital, her skin was too hard to pierce with a hypodermic needle. Her temperature was too low to register on a thermometer. Her face was ashen and her eyes were solid and did not respond to light. Thawing Out Process

''The reaction didn't appear until two or three hours after she started thawing out,'' Dr. Sather said. ''The body was cold, completely solid, just like a piece of meat out of a deep freeze.''