Questions on a limited company.?

I am 50% shareholder in a limited company . I am the secretary, but not a director. The other 50% shareholder died; he was the only director. My questions are: does my 50% automatically put me in charge of the company until the estate is settled? does my not being a director matter? and what exactly is the difference between secretary and director anyway? do I lneed to appoint a director now, and if so, how do I go about doing that when the other 50% is in limbo?