Read here:
If their status at the time of the WP or SP refusal was valid due to the application of R183(6), i.e.,
it was “implied status,” then they will have to apply for a restoration of visitor status if they do not
wish to leave Canada.
5.8. Restoration (Includes instructions found in OB 130)
If a visitor, worker or student has lost their status, they may apply to reinstate or restore their
status in accordance with R182. This regulation only applies if the temporary resident has not
been out of status for more than 90 days, and they have not failed to comply with the specified
conditions.
http://www.cic.gc.ca/English/resources/manuals/ip/ip06-eng.pdf
or
Restoring your status
In some cases, you may apply to restore your status as a student within 90 days of losing it. You may only apply if you have continued to meet the requirements under which you were allowed to enter and stay in Canada and you have met all the conditions imposed on your permit.
www.cic.gc.ca/english/study/study-extend.asp#tphp idtphp