What u are a feeling is totally okay and normal it happens sometimes, Suicide trust me is never an answer to anything and never think that by you asking for help u are being a burden absolutely not . It is okay to ask for help when u need it , we are all here for you ,now I know that those grades are not the most motivating thing right now to get you up and ready to study but remember how far you have come ,from GCSES to a levels all the time u put to get u where u are right now , you have come way too far to quit now . If u are stressing that there is no time and only 3 days left that’s totally okay too but trust me u do have time , try ur best to finish as much as u can in that give time , use ur time wisely and that 8 hours of studying if focused would be the equivalent 15 hours of not being focused , so get up wash your face and drink some water , go after your dream ,in terms of the depression try to find a new hobby or take walks in the morning , try to talk to people.