“Lost One” is the second single from Jay-Z’s comeback album Kingdom Come.
The video was first released on December 4, 2006, Jay-Z’s 37th birthday and notably features the rare concept car Maybach Exelero.
The first verse is rumored to be about Jaz-O, his former mentor and business partner, but is also speculated as being about long-time friend, business partner, and co-founder of Roc-a-fella Records Damon Dash. In the song Jay-Z states, “I heard motherfuckers saying they made Hov; made Hov say, ‘Okay, so, make another Hov.'” Hov refers to his previous stage name Young Hov and the lyrics parallel the history between him and Jaz-O.
The second verse is about Beyoncé. The opening lyric, “I don’t think it’s meant to be, B,” is very arguably addressed to Beyoncé. Jay clarified in Decoded that this verse is about Beyonce.
The third verse is about his nephew, Colleek D. Luckie, who died in a car accident with the car, a Chrysler 300, that Jay-Z bought him for his graduation present. He also mentions Colleek’s girlfriend was pregnant when he died. Jay-Z personally blames his nephew’s death on himself. 
Jay-Z makes a reference to the film “Casino” with the line: “Shoulda stayed in food and beverage/ Too much flossing/ Too much Sam Rothstein.