After repelling the Citadel attack, can I complete quests where the quest giver is missing?

After repelling the Citadel attack, I am unable to find Barla Von and Sellea in Presidium Commons to return their respective quests. Am I too late to ever turn these quests in, or will the quest givers eventually return? If so, when?

Solution 1:

I have been unable to locate Barla Von. After completing Priority: Citadel (third iteration, where you meet with the Asari councilor), the quest has become grey, indicating that it is no longer possible to complete. I conclude that Citadel: Barla Von cannot be turned in after the Citadel attack.

Solution 2:

I was searching for both of them too after the Citadel attack, but I finally found Sellea and he's not where I would have expected him to be.

While the map shows that he's in the Courtyard (4), I actually found him right outside of the C-Sec Outpost (5).

Solution 3:

I am sure that there is virtually NO WAY to complete those side quests after the Cerberus Attack on the Citadel.

Very annoying, especially when they have been completed and all you need to do is talk to a few people.