http://www.gamexchange.co.uk/news/2010/january/mass-effect-2-due-for-release-this.html (Mass Effect 2 Trailer)
The first teaser trailer for the game gave the impression that Commander Shepard had been killed in action, but it was later confirmed that Shepard was brought back to life by Cerberus, providing the player with a chance to change their appearance and character class. Players themselves dictate whether or not Shepard will die at the end of the game based on choices that they make throughout the game. While exploration in the first game had little relevance to the main story, in Mass Effect 2, the player is able to gather resources for ship upgrades and enemy intelligence that will have an effect on the final mission.
BioWare Executive Producer Casey Hudson explained that "If you do die in the ending of Mass Effect 2, it will not come as a surprise, nor will it be random. It will be pretty obvious that you headed into the final mission knowing that Shepard probably wouldnt make it out alive." Hudson also confirmed that team members would be affected by the player’s decisions during the final mission: "You might have an ending where Shepards entire team survives, or where the entire mission is a bloodbath and everyone (including Shepard) is killed, or anything in between." The ending in which Shepard is killed represents a permanent death for the character in terms of the story, rather than a death where the player simply reloads from the last saved game after making a mistake in combat, meaning Shepard will not be available for Mass Effect 3 in that scenario.
Mass Effect 2 begins in 2183, not long after the events of Mass Effect. While on patrol for geth, the protagonist Commander Shepard’s ship, the Normandy, comes under attack by an unknown assailant. The ship suffers extensive damage, forcing the crew to evacuate in escape pods. Joker continues to pilot the ship, despite it suffering extensive damage and the rest of the crew evacuating. Shepard reaches Joker, and orders him to get off the ship. Joker insists he can save the ship even though that obviously wasn’t the case. Shepard drags Joker out of his seat and into a pod, but before he can board himself, the Normandy is attacked again, sending him flying and debris slicing through his suit. He suffocates and dies. His body is seen drifting through space. Commander Shepard’s body is retrieved by the Shadow Broker, a secretive buyer of information, selling it to the highest bidder, who has been employed by The Collectors, an enigmatic and xenophobic alien race who serve as the game’s primary antagonists. In the events of Mass Effect: Redemption, former squadmate Liara T’Soni is employed by Cerberus, a pro-human group, to get the body for the organization, before it is delivered to the Collectors. After this, Cerberus works to revive the Commander through a project known as "Lazarus."
Two years later in 2185, Shepard is awakened aboard a Cerberus space station that is under attack, and aids Cerberus agents Miranda Lawson and Jacob Taylor in escaping. Shepard is taken to Cerberus’ headquarters and granted an audience with the Illusive Man, who explains that Shepard was "upgraded" and asks for the Commander’s help in combating a new threat which has been abducting entire human colonies. Shepard and his team are dispatched to the recently attacked colony of Freedom’s Progress in the Terminus Systems to investigate. There, the group encounters Tali, one of Shepard’s former squad members, and discovers that the mysterious insect-like Collectors were behind the attack. Shepard reports this to the Illusive Man, who then reveals what Shepard’s previous squad members are up to. After receiving command of the Normandy SR-2, Shepard decides to begin recruiting a new team to discover the Collectors’ plan.