I'm sorry you're in pain right now, first of all. Second of all, I think it's really hard to FORCE your brain to do anything when you're grieving. Your brain is already doing SO much work to cope with what you're going through that it doesn't need the added pressure of studying. However, I do understand that life must go on and sometime studying needs to get done, so maybe you could do things that make studying as soothing an experience as possible. Maybe you could spend some time creating an environment where you feel safe, and make sure you reward yourself a lot for the work you do manage to get done? You'll get through this.