After blowing fireworks, i hear ringing in my ears. it has been for a couple hours now. what should i do?

Barotrauma: Should resolve. Machinery, military, shooting ranges etc people wear ear protection to avoid the trauma and symptoms.

Ringing in ears: Sounds like (no pun intended) that you were too close w/o use of ear/hearing protection which lead to damage which you're experiencing as ringing in your ears. It's sunday morning now as i type this answer. If it's no better by this afternoon/evening, plan to go see your doctor in the morning. Your family doc can look for obvious damage & then refer you to ENT for further testing.

Tinnitus: This is tinnitus and can occur from nerve damage from loud noises, it should be temporary, but if it persists you need to see an ent.