The residency requirement for maintaining PR status is 730 days in each 5 years period, unless you are living outside of Canada with a Canadian spouse/common-law partner who sponsored you for PR.
So, if you immigrated via an independent immigration class, and more than 3 years have passed since you landed without your having ever lived in Canada, you have no way to live in Canada now for long enough to maintain your PR status. You'd have to re-apply.