If you are from a visa exempt country, you do not need a travel document. You may however get lectured when you arrive at immigration but as you have not officially lost your PR, they must let you in. You can tell them you have mitigating circumstances, mother with cancer etc. and maybe they will not report you for not meeting the requirements. If they report you, you would have to appeal for your PR listing your reasons.
If you get in without being reported, you can stay in Canada for 2 years without leaving and then they will have to honour your application to renew your PR card because you will meet the residency requirements again. If you apply to renew your PR card before you have 2 years, you would have to list your mitigating circumstances and hope they agree.