There are lots of ways to talk TO them.
The problem is getting a response.
But you can just talk, verbally (maybe going to a spot you know was special to them), or write, or even just address them in your head.
I've found that to be a surprisingly effective way to "communicate" after people have died -- if I knew them well, I'm able to easily imagine what their response would be, which ends up feeling like an exchange. (In this way, I've gotten good advice from people who have died.)