You will need to contact the Canada Revenue Agency’s (CRA) so that they can assist you with your Social Insurance Number since it has expired and they will be able to advise you further.
Also, please note that if your current mailing address is outside of Canada, you will not be able to use NETFILE. Instead, you’ll need to print out your return and mail or fax it to the Canada Revenue Agency (CRA). If this is the first time you are filing a Canadian tax return, you will likely need to mail your return, as the CRA may not have all your information on their files.