I closed my account , will I be refunded by cheque?

Yes. Eventually. It might take a month or two to arrive…

Edit: if post-paid...

If you were a prepaid customer, no refund is available. Only postpaid can have refund either by automatic payment (if you setup) or cheque. More here https://www.koodomobile.com/en/help/things-know-about-cancelling-koodo

Also, make sure you check the final bill from Koodo (the bill generated after the date of cancellation). That bill should settle everything and decide if you have credit or not.