There are 3 different ways to do fix this. All three are quickly detailed here: www.maxkpage.com
What gen(generation) is your ipod touch. I never saw a setting on it that will totally mute the ipod before. Just in case try going to settings. Click General, then go to sound effects. Make sure that Both is checked with a check mark. If that doesnt make a difference get out of general(still in settings) and click music. Go to volume limit, and make sure its off. Also make sure Sound Check is off. Make sure that you have the compatible headphones also. Also make sure the volume is up high enough (you already no but ehh it wont hurt lol). HOPE THIS HELPS.