Without PR Card you can enter back. If it's urgent then you could apply for a permanent resident travel document (PRTD) to enter back. But this should be done outside Canada. Moreover, you can enter Canada through Road via USA if you have US Visa (B1/B2 or transit). In this Case, the Border will accept COPR as proof of travel document.
I have across a post in another thread where the person left without PR card and he was able to enter back to Canada using PRTD.
Sure, I was told about PRTD on this thread itself and it seems helpful, my only worry is, PRTD might also take some time (Lets say weeks) so want to avoid that route. Can you point me to the location of this post you mentioned? Thanks!