Credit Score

$750,000 in debt due to a car accident and now my credit is absolute fucked. How can I improve it? I have no intentions of paying back the $750,000 because well I just don't have that kind of money laying around, and it would take me longer than a lifetime to pay it. My score is currently 450. Will it ever get better if I don't pay back the bill or am I just fucked for the rest or my life?