Trying To Pick Myself Up

hello everyone,i've got a big problem. i'm a student studyin mech. engr. ,as at last semester i was on a cgpa of 4.60(1st class),on monday i checkd my result 4d just completed semester,i did very well but messed up in one course which i had a D,and d course is 3units. nw i'm so down,my heart beats faster than normal. i need encouragemet because my cgpa has dropd to 4.4(second class upper) please i need your advice no insults