bump :(

doublebump.

triplebump.

I´ll answer your question:
You don´t need motivation, you need discipline.
Motivation makes you go to school, when you feel like it. Discipline makes you go every day, even if you really want to stay in bed.

To your life:
Your toxic friends and your brother are bad for you, so you should cut them off from your life. If it´s that bad with your brother i´d consider moving out(depending on how old you are and if you could afford to work).
Cutting them off completely will result in loneliness. But you have to consider, that you are feeling lonely anyway and it will only be temporary. You will find new friends eventually, especially if you are still in school.
Of course you have to do something to find friends, like talking to people you don´t know that well. But in school it should pretty easy to find new friends
Good Luck, I´m sure you can do it :)