I accidentally abandoned the HK-51 quest while trying to reset one of the flashpoints I had to beat to finish it.

 

I tried to restart it on section X, but the droid isn't responding. Is there a way to resume the quest after it's been abandoned?

If you no longer have the underlying quest in your quest log, and the droid on Belsavis is not available to restart the conversation, then you are out of luck, unless a server reset magically blows away some cobwebs, but I would rather throw away money on a lottery ticket than bet on that particular outcome.

 

You can probably do the HK quest on another character and then pay (I think it is 1 million credits) for the character-specific unlock in your Legacy page, but other than that you would need to file an in-game ticket and ask them to reset the quest giver so you can start the conversation again. You will then need to go through the hassle of repeatedly creating tickets to deal with the entry-level CSRs auto-closing your ticket without helping, until you either get a helpful response or ask for it to be escalated beyond the initial handler, or follow up the ticket with an email to support@swtor.com.

Have you tried the other NPCs that are involved in giving you the later steps of the quest chain? You'd have to go back to the one that gave you the step you broke off, as the other quests were fulfilled and thus are no longer available to you. Since you write about FPs it sounds like you already did the Theoretica part and had to collect the 7 HK parts. For Imperials that step is given by an Imperial officer near the crashed ship in the north east of Section X where the daily [AREA] quest is. Not sure who you'd have to go to for Pubside though since I only did that side once years ago.

If none of that works, you should message cs at support@swtor.com, explain what happened, and they 'might' be able to bring it back for you, or at the very least, reset it properly, so you can start again.

Just be polite and concise,

Edited November 24, 2020 by DarkTergon