Any ideas on how to be happy again?

Condolences for your grandparents. Well, this sounds strange, but it's true. We think a lot, but we don't figure it out. The problem is that, the sad thought forms have gone deep into your subconscious and it keeps giving you a long lasting sadness in your life. The reason for how you're feeling is not the deaths in your family. You know yourself that these happened and it's time for you to move on. But you're still stuck where you were. That means, your mind is pushing you into that phase again, not allowing you to come out of that. When you're going through this, if you find yourself laughing out loud for joke you weren't expected to hear, the next moment you'd think "I'm not supposed to be happy... How can I laugh like this?" Even when you don't come to know you think this, that will be in your subconscious. The first step to get rid of that is to realize this and then take control of your mind. Don't let your thoughts waver. Your subconscious and the thoughts planted deep in it, control your life. So keep your mind and body healthy. You'll be fine. If it makes you feel any better, get yourself a routine and start working out if you like. Having a routine and especially physical exercises are helpful in cleaning up your mind upto some extent. Good luck.