you are probably crossing a bad moment in your life and it's happen to everyone. Stop telling yourself that you can't do anything good in your life ( i know because it's happen to me sometime ), and go ahead , keep going. And about yours friends , you should probably listen to them and let them help you , there is absolutely no shame to have.
Stop telling yourself that if you desappear no one is going to regret you , that is totally a wrong idea , you probably have a family to help you finding your way. Again , go ahead , success your studies , find a job you like and everything will be allright.
It's a good idea to come here and tell us how you feel , i'm sure we can help you
And finally , don't hesitate so speak to someone ( family , friends , psychologist etc ) , believe me , it help a lot