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It very sad that you lost your father, and the symptomatology you are showing as social withdrawal, crying spells, feeling depressed, low mood, loosing friends all are due to the loss. It a a normal grief reaction. But it has been said that grief reaction is normal for up to 6 months, if it prolongs more than 6 months then it may lead to depression
and other mood disorders
. Its life and one has to move continuously despite many setbacks. You have to come out of it otherwise if will hamper your life, your education, your occupation, and also it will cause burden to your family.
Try to share your grief with some close friend. Try to indulge in social activities, you can talk with any family member regarding your problem. Try to keep attention away from this by participating in some constructive work. But if condition worsen you can visit a good psychiatrist
or counselor for proper management.