It's not clear from your comment whether you had a valid study permit during this 1 year period? If you did, you had legal status(no matter if the student visa had expired). Otherwise, you stayed in Canada illegally.
Assuming your study permit had expired, had you noticed it within 90 days of the expiration date, you could have applied to restore your status and not had to return home(assuming CIC approved it).
Anyway, you returned home which is good and indicates some willingness on your part to abide by rules. A prior history of overstaying will make things difficult and your burden of proof much higher. However, if you don't try you won't find out. The worse that could happen is they say 'No'.
You can apply for a study permit and visa again and include an explanation of what happened. That is, how you came to be out of status, what you did to regularize your status, when it failed you returned home, what you will do/have done to ensure it doesn't happen again - you don't want them thinking you couldn't be bothered about obeying their rules.
If you can, get a letter from the Dean of your faculty/program that confirms only 4 courses are left for graduation and submit it with your transcripts. If a visa officer looks at your application favorably, you may be interviewed and they would probably want to know what your plans are after graduation if granted a visa. This is a tricky question for 3 reasons:
1. as a student, you must demonstrate that your intentions are temporary in nature
2. on the otherhand, you may want to gain work experience and immigrate(but remember your plans have to temporary?)
3. if you say you will return home, will it be convincing to the officer?
Not sure what's the best answer(lol), but I know that if I studied in another country, I would want to have some work experience in my field of studies and potentially apply those skills in my home country.
Best wishes in your endeavours.
