If your study permit expired a year ago, then it's too late to fix anything from within Canada. You'll need to leave Canada to fix your status. Once you are back in your home country, you'll have to apply for a new study permit. It may be quite challenging to get one approved given how long you have been here without authorization.
Unfortunately this also means you won't qualify for a Post Graduate Work Permit since at least some of your studies were completed without authorization. If you can get a new study permit, you may want to consider starting a new program so that you can qualify for a PGWP once you complete your new program.