1. If you are visa exempt to Canada, you could attempt to enter Canada and see what happens. If you are allowed to enter without being reported for not meeting the residency obligation, you can take up work with your SIN card and go about your daily business. Because you do not have a PR card, you may face difficulties getting a health card and a drivers license but you do have your landing papers so that should help.
If you live in Canada for 2 years, you will meet the residency obligation again and would be able to apply for a PR card stating that you lived in Canada for 2 out of the past 5 years and they would have to give you one.
However, if they were to report you on entry, you would have to appeal for your PR, giving your reasons for not being able to live in Canada and see if they let you keep your PR.
2. Another option would be to apply for a travel document at a Canadian embassy showing proof of your mothers illness and taking care of her for the past 16 years. People are often given a travel document in order to return on those grounds, however, 16 years is quite a long time. If they were to give you a travel document based on humanitarian grounds, you could return to Canada and apply for a PR card right away based on that travel document. If the travel document is denied, you can appeal. If you don't appeal or lose the appeal, you lose your PR.
3. If you lose your PR, your daughter could currently not sponsor you for PR because sponsorship for parents is currently on hold, see http://www.cic.gc.ca/english/immigrate/sponsor/relatives.asp However, she may be able to sponsor your when the program re-opens. Immigration may be planning to increase time of the sponsorship commitment for parents and/or income required. Currently, if you lost your PR, your daughter could only sponsor you for a super visa, that is a visit visa where you may stay in Canada for up to 2 years at a time. You would have to buy health insurance because you would be a visitor and not eligible for health care.