The technical term for where you've arrived at is "mid life crisis" - albeit a bit earlier than most.
Your search for success is over. So the next step becomes the search for significance.
First though, as others have said, your "what to do next" is colored by the natural grieving process you need to go through. Accept that your emotions will likely be all over the place for a while. This isn't a time for big decisions, but rather smaller, quieter, times for you to find a new simple routine.
Once your life has returned to (emotional) normal, then you can start the next chapter. Being significant means making a difference, on the people around you, on your environment, and so on.
Like with most things, there's no "quick path". You need to try this, try that, and see what sticks. Local charities are always a good place to start (they can use the help) but they may just be a stepping stone till you find your place. Interacting with youth in some way (school, church, clubs etc) can also be very inspirational (for you and for them.) Kids like to hear stories of success (they're still on that path) and hearing it from someone young - closer to their own age - really sticks.
Most of all, don't panic if you wake up tomorrow with nothing to do. You've got a long road ahead. You don't need to rush. Take some time to just settle down. Maybe go on a trip to somewhere peaceful.
Charities- yes, and: consider the concept of mutual aid as well. In-the-mix helping others, and being helped reciprocally (but not transactionally) is potentially more meaningful than helping through charitable giving, though given our dominant paradigm of capitalism, charity is certainly helpful too.
Your search for success is over. So the next step becomes the search for significance.
First though, as others have said, your "what to do next" is colored by the natural grieving process you need to go through. Accept that your emotions will likely be all over the place for a while. This isn't a time for big decisions, but rather smaller, quieter, times for you to find a new simple routine.
Once your life has returned to (emotional) normal, then you can start the next chapter. Being significant means making a difference, on the people around you, on your environment, and so on.
Like with most things, there's no "quick path". You need to try this, try that, and see what sticks. Local charities are always a good place to start (they can use the help) but they may just be a stepping stone till you find your place. Interacting with youth in some way (school, church, clubs etc) can also be very inspirational (for you and for them.) Kids like to hear stories of success (they're still on that path) and hearing it from someone young - closer to their own age - really sticks.
Most of all, don't panic if you wake up tomorrow with nothing to do. You've got a long road ahead. You don't need to rush. Take some time to just settle down. Maybe go on a trip to somewhere peaceful.
Good luck.