You will have to
get in touch with B & W and see if they can rebuild the drivers you blew, or supply new drivers. You have to use B & W drivers. If B & W can not rebuild or replace those drivers because they are out of parts, then you have totaled that set of speakers.
I assume you cranked ghastly rock music through them, for which they were never designed.
I think this is the speaker you are talking about, is that right?
Those date from 1986 and were among the last speakers designed by John Bowers, before his untimely death.
I think it doubtful those speakers can be repaired, because of their age, and that's a pity. If I remember correctly the bass drivers had Bextrene cones. This is a plastic polymer that has not been made anywhere in the world for a few years now. So unless they have some old cones that will put you out of luck.
One option is to search eBay and see if any are getting parted out, however with those speakers that is unlikely. It is more likely a set of those speakers will come up on eBay or Audiogon complete.
The descendants of those speakers is the current B & W 800 series loudspeakers. The closest descendant of that speaker is the 802D. I think the woofer in your speaker is somewhere between 10 and 11 inches if my memory is correct. The 802D uses two 8" Rohacell drivers in place of the single Bextrene. Unfortunately the cost of the 802Ds is $14,000 per pair.
However in their day your speakers were comparably priced when corrected for inflation. So unfortunately, I suspect your father will not be too happy, but I suspect he will come to forgive you.