There is a home remedy that might work on woolen sweaters shrunk just a few sizes. Pour two tablespoons of regular hair shampoo [ which will relax natural fibres but not on synthetics ] into a bucket filled with cool water. Soak the sweater in the solutiion for 30 minutes, then gently squeeze out the water. Do not rinse. Lay the sweater out flat on a towel, then roll it up to absorb the excess moisture. Lay the sweater out again on a fresh , dry towel and try to gently stretch it back to shape, but do not pull hand.