Your 401(k) (generally) is protected in bankruptcy as an exempt piece of property.
(xiv) except as provided in Subsection (1)(b), any money or other assets held for or payable to the individual as a participant or beneficiary from or an interest of the individual as a participant or beneficiary in a retirement plan or arrangement that is described in Section 401(a), 401(h), 401(k), 403(a), 403(b), 408, 408A, 409, 414(d), 414(e), or 457, Internal Revenue Code;
Your 401(k) loan is simply a loan you have taken out from the 401(k) (your own retirement money) for some immediate purpose. Bankruptcy doesn’t discharge this debt, because it is a debt that you owe to yourself. You simply keep making payments back to yourself (401k) after filing.