I need to know which game ME1, or ME2
In ME1 she really doesn't have one, not truly, you don't have to take her on the Noveria/Peak 15 quest, and she doesn't really have a loyalty quest.
So I will be an ass, and assume you mean her Ilium quest in ME2, where you have to hack the all the security nodes, and download the info. All I can tell you there is to look around Ilium, the nodes are there. If your looking for her office, look for the words administration, in big letters, and go up the stairs, open the door, talk to the receptionist, and go see Liara.