Depressed friend. Need advice!

I have a close friend who has fallen into depression. His mom died. His dad got a new family to replace them and won't talk to his bio kids anymore. I want to do something to help my friend and let him know that he isn't alone and that there are still people who care for him and love him, but he won't answer my calls or texts. We live in different states, so I can't go see him because of covid travel restrictions. What else could I do to help him? Its been a year and he still will only talk to his sister. I want to help him, I just don't know what to do.