Hello
First of all I appreciate you asking for help. That is the first step towards recovery.
I understand you are going through a tough time in your life. Competitive exams can become overwhelming. Such times can act as stressors which can increase one's vulnerability towards mental illness.
From your description, It appears that you are suffering from Depression.
Next Steps
You should reach out to a psychiatrist. After an interview, you may be prescribed a course of antidepressants. (example 50 mg of Sertaline at night, tablet Rantac in the morning empty stomach and Clonazepam 0.25 mg for sleep disturbance or anxiety- but better to see a psychiatrist personally)
Try to take out time for yourself everyday- like gym, walking, cooking or anything you like.
try reconnecting with friends. The idea is to connect to a social circle.
Health Tips
Many of my students have faced similar situations. They really improve with medications. But a few go in denial that they don't have Depression, which adds to their problem.
Go and see a Psychiatrist.
I wish you a speedy recovery and a bright future ahead.
Life is more than exams.