If you use Bitlocker it’s "really really" important to have access to the recovery key, as the result of not knowing it may prove a painful experience. Remember, no key means no access!
I guess, when reflecting on the IT issue of last Friday one should have a few backup plans in place – a backup of your IT and a “how we will keep working while a system fault is being resolved” plan. And, these plans should be reviewed on a regular basis.