As reported by the Associated Press, via US News & World Report, the IRS says that it
cannot locate much of the email sent by a former IRS official over a two-year period. "The IRS told Congress Friday it cannot locate many of Lois Lerner's emails prior to 2011 because her computer crashed during the summer of that year. Lerner headed the IRS division that processed applications for tax-exempt status. The IRS acknowledged last year that agents had improperly scrutinized applications for tax-exempt status by tea party and other conservative groups." Three congressional committees are investigating the agency because of the allegations of politically motivated mishandling of those applications, as is the Justice Department and the IRS's own inspector general. As the story says, "Congressional investigators have shown that IRS officials in Washington were closely involved in the handling of tea party applications, many of which languished for more than a year without action. But so far, they have not publicly produced evidence that anyone outside the agency directed the targeting or even knew about it."
CBS News has a slightly different version, also based on the AP's reporting.