Is it okay to show up at his job?

My boyfriend and I have been together for five and a half years. All of a sudden last week he stopped calling, texting and I can't get ahold of him. I haven't seen him in twelve days. All romantic heartache and pain aside, I have bills for him and important mail for him. I've been texting and calling him but have been trying not to smother him in case something is wrong. I feel like he's broken up with me cold turkey without telling me. I know he's been showing up to work because I drive by it every day on my way to my job. Since he won't reply to me or let me know a time he can come pick up the bills, etc, is it okay to show up at his job to give those things to him? I'm very, very upset about this and think I might not be thinking straight but there are things he needs to take care of as we've been living together for the past four years and he has made commitments--like to our cellphone bill, car insurance, rent, etc, all of which is combined together. I don't want to make things worse by showing up at his job but I don't know what else to do. Any help?