I know where the nightgale is and the queen of Veldt gives me the quest.
I have the birdcage, I haven't started the quest so I can't take the bird seed. The queen won't say anything but "Welcome to my kingdom".
How do I "activate" the quest? Am I missing something?

You need to get the genie lamp from the Demon Caverns for the Queen first. After fighting (one of) her husbands, you can then notice the Queen hasn't been sleeping well and get the quest from her.

The funny thing is I can't find it.
It's sopposed to be here? Image
I fought a demon and got a soul here. I'm kinda clueless.

Yes, that's where the lamp is supposed to be. What soul did you get? And what demon did you fight? Which build do you have?

Build B, the soul of druid of the stronghold temple (I can't remember the name) I think was Tawrich but possibly Saurva. I did this quite a while ago.

Then you should be able to get the quest. Is the corn still in the hideout by chance? If it is, then you need to finish the quest concerning the corn.

The corn is gone, you can check it out in my save file if you want.
My save file

Have you returned the soul to the druid? Have you brought the druid to the sun temple?

Yes, I've only got to take the druids of light and time to get them all.

Call me crazy, but I think you've actually got Build A, in which case the Empress of Veldarah will be the one to give you the nightingale quest. Just out of curiousity, where did you fight the daeva holding the soul of Vohu Manah the Bard? In the temple basement or on top of Mt Orion?

Hey I think your right, it was the temple basment.
Edit: YAY! It worked, thanks!

Haha, glad I could help!