How to deal stress. Pass my exam well!

Hi my name is Triyambak 19yrs i was very good in studies in class 11 nurture Student of allen was top 10 but in class 12 i changed my hostel the biggest mistake i done there i have no friends as it was not good hostel therefore after class 11 students leave that hostel in 12  so no 12 student there Only me became average student became depressed no school passing days Develop new disease k/a telogen effluvium Hair loss reduced to turtle Study by myself later i left preparing for board Now i do not know i am in depression feeling sad not taking to anyone isolated and do not have any fear of exam just chilling at home 24 exam will start planned to score some 80 90 Going to that hostel again for 20 days exam throat burning food is served there because at home i eat simple food please tell me how to not be depressed again and pass my exam well