I don't believe there is a way to "get your mother's birth recognised by Canada.". Nor is it necessary to do what it is you are trying to do. If it was never registered, I suspect it's moot at this point.
I'm not sure what search you referred to above, but if you haven't already, I would suggest submitting a request to search CIC's citizenship records http://www.cic.gc.ca/english/citizenship/search.asp for proof that your mother was granted citizenship.
Alternatively, you could gather up as much information as possible and apply for proof of citizenship for yourself : http://www.cic.gc.ca/english/citizenship/proof.asp This would be your way of asking CIC to make a formal determination as to whether or not you are a citizen.
I suspect that your case would require special consideration since it isn't cut and dry, and it is likely to be denied if you have never established significant ties to Canada. A lot of people think they are Canadian citizens when they really aren't, due to not being fully aware of the laws. I don't know your whole story, but some "lost Canadians" have even lived in Canada since childhood but find out that they aren't citizens when trying to claim retirement benefits. For those who have spent most of their lives outside Canada, the suspicion is that they are trying to now claim direct citizenship so they can benefit from health/social benefits and/or assistance. Like I said, I don't know your whole story, so....Good luck!