If i try to sleep i can't stop thinking about my father that dies 4 months ago?

I am sorry for your: Loss. Clearly this has really effected you. I would encourage you to work through your grief. You can do this with supportive relatives or friends, a member of the clergy (pastoral counseling) or a therapist. Then you can set a boundary for yourself , that the time just prior to sleep will not be used for grieving. I know it sounds odd - but you can actually program your mind to turn off the >>.