Hello my friend...just remember "Broken heart and shattered dreams are key mentors for weaving a glorious destiny."...Consult nearest psychiatrist as you require detailed counseling session and you may require medications to solve your problems as many things can't be discussed in forum like this...With that fallow relaxation techniques like yoga, meditation,avoid alcohol, smoking, coffee, tea...have good sleep and develop healthy food habits..good luck

There will be a reason behind your disinterested attitude. Probably,  you wouldn't have thought about it. Do consult a psychologist and find out better ways to handle yourself