Canada uses very little cash and when I was in Iceland I never even saw an Icelandic Kroner. Using debit and credit can be a useful tool IF the networks are up and there aren't long lines at the ATM. I've heard this isn't always the case in Nigeria.
So sorry you had to go through that bad situation. Hope things get better there but from what I've been reading it could be a long road.
Nigeria is the opposite of everything happening in most countries, its been years and things are still constant lets just hope the new government makes it better