Deus Ex: Human Revolution

Walkthrough:

Part One:
Jensen must meet with Pritchard in his office first, before going up to Sarif's penthouse after coming back from the FEMA facility. Then Sarif will most likely be the third dialogue challenge the player attempts, after Zeke Sanders and Wayne Haas.
Jensen can either appease the confident, assertive CEO by insisting he needs the information to help his boss, put the focus directly on the backdoor tunnel and claim it as a dire security matter, or go on the defensive, asserting that with his service (especially on this particular day), he deserves to know and Sarif should not hide any security secrets from him. With the Social Enhancer augmentation, Jensen can also threaten to quit, alarming Sarif's Alpha personality. If successful, Sarif will spill everything and even forward the emails from the private investigator to Jensen.

A surefire method without any extra benefits from the social enhancer is to choose the Refocus option three times, politely and efficiently keeping the subject on the backdoor access, despite Sarif's attempts to change the subject or distract Jensen by semi-goading Jensen. After the third Refocus option, Sarif will be leaning on the back of his chair. Choose Defend for the fourth and final chance. If you have the social enhancer, David's persuasion will rise the first two Refocus options, and drop a bit on the third. The Defend option will raise it back up and score the information. When you are finished with the succusful dialog challange you will unlock this achevement.


YOU MUST return to Jensen's office to READ THE EMAILS sent to Sarif from Brent Radford. If this is not done the second part of the quest WILL NOT TRIGGER upon the return to Detroit. The emails cannot be read after the return because the Sarif building will be locked out due to the riots.
This part of the quest is over for now, though the player will learn some intriguing details from the private detective's emails.



Part Two:
Once the player returns to Detroit from meeting with Eliza Cassan, Pritchard will contact Jensen at the Convention Center and set off the second phase of the quest.
Upon arriving at Radford's apartment however, Jensen will find an armed suit that must be dealt with, and a severely wounded Radford. Radford will refuse to speak with Jensen until Jensen retrieves a trauma kit in the closet and give Radford a shot of morphine. It turns out the detective is another purist who despises augmentation, and though he's ultimately willing to cooperate, he has nothing but disdain for the "robot", Jensen.

Radford will direct Jensen to his storage locker, and to find a woman named Michelle Walthers for further answers. Then he will ask Jensen to euthanize him - he recognizes his wound is serious and even if he survives, he will likely become a paraplegic. Refusing to either get augmented as he despises augmentation or live for the rest of his life in a wheelchair, Radford would rather die whole and needs Jensen to do it as he can't do it himself.

Jensen can either bully Radford into living, convince him that life would still be worth living, or convince him that augmentation isn't that bad and even the robotic Jensen is still human. Keeping Radford alive at this point is strictly optional. Euthanizing Radford will grant the achievement

and will NOT count against the Pacifist achievement.

Radford's security locker is in the alley near the police station. Several armed men in black will be there and must be dealt with; however, police are nearby as there has been rioting in Detroit, and if they hear any gunfire they will become hostile. At this point, the quest comes to an end unless Jensen can hack the safe (or uses the code 4062) in the locker where he retrieves a few photographs of his baby self. It is also necessary to hack the computer (level 3) or password *sparky* and read the last email.

Next Jensen must track down the mysterious Michelle Walthers. Upon reaching her apartment, he finds that she is a nice but senile elderly woman, who mistakes the heavily augmented Jensen for a Meals on Wheels deliveryman. Jensen will play nice and pretend that he is talking about someone else, but he will need the baby photos to proceed.



Personal note:
I found the rated solution not as helpful. Really does not give any walk through info. Also doesn't even tell you about the other two achievements that you can get, a long with not affecting "The Pacifist" achievement if you are also working on that as well.
None of this is my work I took it straight from the source here. I did however tweak it a little bit.
http://deusex.wikia.com/wiki/Acquaintances_Forgotten
Credit to SoulyDconte for the lvl 3 computer password.

Before you depart on your first trip to China, Pritchard will contact you and alert you to a security hole in Sarif's system. Go and complete the objectives that this update brings. Once this is done you will be given the option to confront David Sarif in his office, do so. After completing the speech challenge go back to Jensen's office and read through his newly updated emails. You can talk to Pritchard again if you wish once you've done this.

After that is completed you will depart to China, don't worry about this quest there. After your business is completed you will fly back. When you return to Detroit you will be contacted by Pritchard again on your way to a primary objective and it will initiate this side quest. Go through the objectives and complete it and you will unlock the achievement.