Technically, no Donald Trump himself has not filed for personal bankruptcy, but companies he has ownership stake in have. So both statements are true, at least, in a legally defensible sense.
This was covered on NPR's All Things Considered recently, Scott Horsley analyzed the statements thusly, from "Fact Check: Fiorina's HP Record; Trump's Bankruptcies; Vaccines And Autism":
Well, you can hear Trump saying in the background, I never filed for
bankruptcy. He is right when he says he never filed for personal
bankruptcy. But Fiorina's also correct when she says Trump
corporations turned to bankruptcy court on four different times to
reorganize their debts. Trump has defended that as perfectly legal
under the law and, of course, it is. Most of those bankruptcies were
tied to Trump casinos in Atlantic City. The debts were restructured.
Trump's ownership stake was whittled down. And like Fiorina, he says,
look, context matters here. Just about every casino operator in
Atlantic City has struggled, and those bankruptcies represent a small
fraction of the many business deals he's done.
From "What Trump didn’t say about his four big business bankruptcies", Washington Post
The 69-year-old real estate tycoon has never filed for personal
bankruptcy and has for years portrayed the Chapter 11 bankruptcies of
his glittering hotels and casinos as calculated, even shrewd
maneuvers, and facts of life in the high-stakes worlds of
mega-development and commercial finance.
According to one estimate, Trump's bankruptcies have accrued around $4.7 billion worth of debt. I'm not sure if there is enough information to calculate exact total losses. In some cases he still owns a limited amount of stock in some of the entities.
From "By the Numbers: Donald Trump’s $4.7 Billion in Bankruptcies", Dividend Reference