Remove spaghetti noodles from the carpet with a fork. Carefully scoop up the pasta and discard it in a trash bag. Continue this until all of the noodles are removed from the carpet.
Scoop excess spaghetti sauce off the carpet with a spoon.
Pour cornstarch over the stain to absorb the oil and liquid from the sauce. Leave the cornstarch on the carpet for 10 minutes. Vacuum the cornstarch from the carpeting.
Pour 2 cups of cool water into a bucket. Add 1 tablespoon of dishwashing detergent and stir to mix well.
Dampen a clean cloth with the soap solution. Dab at the remaining spaghetti sauce stain to lift the color. Move to a clean portion of the cloth and continue to sponge the stain.
Press a damp cloth into the carpet to rinse off the detergent. Treat any remaining spaghetti stain with a solution made from 1/2 cup of cool water and 1 tablespoon of ammonia. Sponge the stain until it's removed.
Rinse the carpeting with a damp cloth. Absorb moisture from the carpet with dry cloths until no further dampness is absorbed into the cloths. Allow the carpeting to air-dry completely.