How to become a brilliant student from a below average student?

Hi,
I completed my college studies and want to pursue my masters immediately this year. I took my GMAT for the second time and it was inadequate for admission into any schools in US. I feel I am so dumb. I badly want some advice from an expert how I can prove myself.
After two days of my GMAT exams , I felt so motivated and confident to somehow study, cramp and beat the gmat. After weeks I feel so demotivated to study for the exams so devastated I cannot concentrate in studies.
I donot know why do I feel this way. When i see other students I do get that thirst but after sometime it is all quenched I donot see the same motivation and the pressure like before.
I want to bring back my confidence level, make use of my knowledge,improve motivation and somehow do well in the exam.
I donot see the passion for studies now as I am mostly motivated into fashion, partying and celebration . I cannot concentrate on studies. Please give me some advice as to how I can study with my heart and soul.