If your parents had applied for citizenship, they would surely have applied for the children as well. If you were a small child, you would not have needed to do anything to get citizenship on your parents application. I find it unlikely that they would have gotten citizenship and never told you about it but who knows. You can use the link I gave you in my last reply to ask for them to look for citizenship records for yourself as you may have become a citizen if your parents had applied for it which you don't know. If any of your siblings were born in Canada, they would be citizens but it will not help you to have a citizen sibling unless they live in Manitoba or Saskatchewan and are willing to sponsor you through PNP family stream.
1. It is possible that your parents became citizens and applied for citizenship for their children as well. If that is the case, you would still be a Canadian citizen and once you clear up the paperwork, you can live in Canada and sponsor your husband and minor children for PR.
2. It is possible that your parents applied for citizenship but did not include you children on the application. In that case, you would have no right to anything because you would not be a citizen unless your parents had applied for you or were already citizens when you were born.
3. It is possible that your parents and their children all had permanent residency. This status is given to people who want to permanently live in Canada without gaining citizenship. If you don't live in Canada for some time, you lose this status. Since 2002 or 2003, it has been 2 years in every 5 year period you must live in Canada to keep this status. Before that, it was 6 months in each 12 month period. After 40 years outside Canada, you surely would have lost it.
There is a loophole that if you had PR and you have not officially lost it, you could go to Canada and stay for 2 years and then you meet the residency requirements again, can apply for a PR card, sponsor your family etc. However, it would be very hard for you because you do not even know if you are PR or not. You do not even have old landing papers or a social insurance number. You would have problems getting health care activated or legally getting a job. Did you find any papers in your parents things regarding Canada immigration? The problem is, if you ask immigration to check if you are a PR, they will see that you have not been living in Canada for 40 years, they will say yes you are but now we revoke your status because you don't meet the residency requirements.
4. It is also possible that your parents were in Canada on a work permit without every getting any permanent status in which case, you also have no rights.
Can you ask an aunt or an uncle if they know anything about your parents status in Canada back then?