Hello Vandal ... I know that you are definitely eligible to do the Toulan Born beginners mission chain, and if you abandoned this one particular part of the mission chain, you should be able to take it again. Masoud's mission to kill the 5 Qaffaz is the first mission right after getting Ahlan's old vehicle, and you should be able to continue from there ... go back to Ahlan at the Citadel and see if you can click on that NPC who sends you to Masoud ... if not, and you can't click on Masoud to take that mission then Kendra might have to look at this.
Is there anything showing in your Mission Tracker for this mission ... did you abandon the mission through your mission tracker? If you've done all of these things, then it will have to be looked into. Can you take a screenshot of your mission tracker to show that the mission is in fact not listed and post it here, would appreciate it ... thanks.
I have something to do before I log into the game, but when I do then I can meet up with you to see if we can sort this out.