To get ungrounded, it may be necessary to show your parents that you're responsible and know how to manage your time. Picking up extra chores around the house could be an effective way to do this.
Your parents may have a list of tasks for you to complete before you can be ungrounded. If this is the case, be sure to do each task to the best of your abilities, without complaining. When your parents see that you're cooperating and have a positive attitude, you may be ungrounded sooner. If the reason you were grounded had something to do with not getting along with a family member, make a special effort to show love to that family member while you're grounded. Your parents may reward your good behavior by shortening the length of your punishment.