I find that when I feel helpless about the state of the world, or even lacking control in the little and big things in my life, Metta meditation, from the Theravada Buddhist tradition is my go to practice.
Here it is:
Be comfortable. Start with a few deep cleansing breaths. You might be seated or even laying down. It's nice to put a hand on your heart, cultivating awareness for your heart-space...perhaps just by noticing the sensation of your own beating heart. We can take a moment to think of the boundlessness in the heart; your heart has no limits on who you can love or care for....your love and care are limitless.
It's helpful to think of someone (past or present) who loves or loved you unconditionally (a parent, grandparent, sister, friend). Bringing an image into your mind of that look of care and love by another. Then we start with ourselves (keeping in mind that you can't give away what you don't have for yourself). Direct the meditation to yourself and silently repeat the following phrases:
May I be happy
May I be healthy
May I be safe and protected and free from harm
May I be at peace
Silently repeat that towards yourself a few times.
Then we start to send it out to someone we know might need more happiness, good health, safety, and peace (someone you can imagine easily sending these wishes for well-being).
May they be happy
May they be healthy
May they be safe and protected and free from harm
May they be at peace
At this point it's helpful to reconnect with your own heart; the sensation of your own heart beating and recalling that person who loved or loves you unconditionally. Finally, remembering the boundlessness of your own caring heart, start to extend these wishes towards all beings near and far. Then silently repeat to yourself:
May all beings near and far be happy
May all beings near and far be healthy
May all beings near and far be safe and protected and free from harm
May all beings near and far be at peace
This meditation might or might not change the external things in your life or in our world directly, but it will work to change your own compassionate heart, bring you a little (or a lot) of peace, and will have a lovely ripple effect out to your community and beyond.
"Just as ripples spread out when a single pebble is dropped into water, the actions of individuals can have far-reaching effects.” Dalai Lama