Reputable journals will waive publication charges for authors who cannot pay them, so you should ask about that. If everything goes well, then that will simply solve your financial problems. I see only two ways you can get stuck:
(1) The journal insists you can pay, perhaps because your advisor has plenty of grant money, but your advisor refuses. In that case you have a serious problem, and it is much deeper than just paying for these publication charges; you need to sort things out with your advisor.
(2) The journal does not have a procedure for waiving the charges. In that case, the journal acceptance is worthless. The journals in this category are money-making operations with no academic validity. Nobody will care that they accepted your paper, because they just wanted your publication fees.
The first thing you need to determine is which case you are in. For example, one valid reason for an advisor to refuse to pay is because the journals are not reputable. If you are in that case, then you need to rethink everything. Otherwise, it sounds like you may be in a complicated situation with your advisor.