The key to my broken heart

What has been done can't be undone. What has been broken can't be fixed What has stopped can't beat/rise again and a broken heart can't be healed.

But can it be turned around? Can something that has been done be undone? Can something that has been broken be fixed? Can something that has stopped beat again? Can a broken heart be healed again?

Even though all this doesn't work out, even though it's fixed but a part remains the same, can all this be done?

Can these two find the key to healing their broken hearts?