If a judge in PA sentences someone far above the maximum for a crime and a lawyer discovers this, what happens

Someone I know was convicted of a misdemeanor. The judge sentenced them to 2 1/2 to 5 years in a state prison! no one understood how this happened..the case itself was weak...nevertheless, the elderly judge did this and the new lawyer on the case found that with this person's history along with this conviction the maximum sentence should have been sixty days! What happens now? (they have been incarcerated for almost a year now...) can the person sue the State?