So the woofer is now OK but the inductor from the crossover came off? Solder it back on.
If you can't (but I don't see why) then you can either contact Focal and ask what the value is (or for a replacement inductor in any case) or find out what the slope and frequency is for the crossover, then either find something "close enough" or have someone design one for you and build it etc. "Close enough" sounds much more appealing.
EDIT: Doh! The x-over says on the cover that the slope is 12dB/oct. All you need is the cutoff frequency and you should be able to get a full x-over replacement for low coin. It'll lack quality components but you don't really care.