Yep, go for it. I was given a jar of starter that was in the back of a neighbor's fridge for a year. It had black stuff inside all around the top. It smelled totally gross.
I fed it, if I remember correctly, about twice a day. For several days, although it did not smell as bad, it did nothing. A few bubbles at best, no rise. Suddenly, around day 4 or 5, it started growing! After another feeding or so, it doubled and it started smelling fresh. I am still using it now every week, etc.
You need to be patient. And, it is just flour and water and a few minutes of your time. No big deal if you get a fail.