If you have registered for MY Account, you can log in on CRA website and find the copy of T4. Otherwise, you can call 1-800-959-8281 to ask. If your former boss did not file T4 for 2013, he will be penalized for not remitting CPP, EI and filing T4 late. Give him a warning that you will file complaint to CRA if he does not issue T4 to you.