Can you raise investment or sell the company outright ? - if you've got millions of users then it might be viable route.
Sell might be an option. One of those things where there was an offer a while back, perhaps they will take it for a song. But otherwise, how to go about it?
Who do you primarily owe money to ? - if a significant chunk is to a supplier then you might want to see if you can negotiate a deal with the supplier writing off the debt in exchange for equity in the company.