Too late now, but for future reference...
Before I explode a solid, or extrude a complicated profile, I save a copy of it to a layer that I have simply called "Backup". This layer stays turned off, and If I need something, I just turn the "Backup" layer on, and reuse whatever I need. Once you explode or erase, and you close ACAD, it is pretty much lost for good. Sometimes I am able to recove an older automatic-save, and pull the parts out that I need.
Flores