So you took the GMAT and are not happy with your score.
First and foremost, you should not be feeling depressed by your score, even if that score is not what you wanted or what you expected. The GMAT is often difficult to do well on. Take the next few days to assess what you did to prepare, whether you did as much as you could or should have, and how you could have done more to ensure you have the score you wanted. Assess whether the course you took or tutor you worked with was really in line with your learning style and whether you should have recognized that earlier and done something to make the course or tutoring more effective. Finally, stop beating yourself up if you did not get what you wanted or expected. It often takes a couple stabs at the test before you settle down enough to achieve your best score. To provide you some perspective, the arithmetic mean (a little GMAT speak for you) score is 538.5 and 79% of test takers score below 650, according to the Graduate Management Admission Council.