how do I get help

im depressed. usually i get out of it for awhile and then it comes back for a little. this time i cant seem to get out of it. i dont have any motivation or self confidence and self worth. im not doing anything, im failing my classes, i cant look at my friends anymore. when i do i feel ashamed and disappointed in myself. no matter what people say it doesnt seem to help. i talked to my mom about some of this but it didnt help and it seems she forgot about it. im scared to tell everything to the people i know. im scared to ask them for help. i dont think they will understand or laugh at me. is there a place i can get discreet help? i dont want to be here any more. also, for those of you who cut, what is it like? why do you do it? sorry if i seem rude or ignorant. i want to disappear