moldy starter!

I'd chuck it and start over. You don't want to mess around with mold spores.

From what I've read and experienced there is no need to abandon your starter. When I first started mine I saw some mold on the side of the jar and near the top  (about day 4  or 5). I transferred a bit of my starter to a clean (sterilized) jar and moved on from there. I have not seen any traces of mold since, and my starter is just fine. I realize that your starter is older, but it is worth giving it a shot.

Polo

This just happened to me because I skipped a feeding. I'm generally forgetful, so it's not the first time.

Mine smells cheesy when this happens. I've rescued it several times by saving a 2 teaspoons and feeding as normal, but every 8-12 hours. It normally springs back to health after 4 feeding cycles. 

I've never had mold all over the container, so who knows. 

Jacob

This is what I've done with good results.  Wash a handful of spoons.  Ones long enough to reach to, and a bit below, the starter.

Mold is generally a surface condition - if you read medical history a major issue in cultivating anti-biotics was that mold usually stays on the surface so the yields were too low.  For us, this is good news as the starter is likely to be intact.

Scrape off the mold from the surface of the starter.  Change spoons frequently.

If the top of the remaining starter is discolored , scrape that off with fresh spoons.  You want to get to a light colored layer.

Once you are into the light colored layer, use a fresh spoon to take out a teaspoon of the remaining starter and put it into a clean bowl.  Put the rest of the starter back into the fridge in case you need to repeat this process.

Whisk in 1/4 cup of water and then 3/8 cup of unbleached white all-purpose flour.  I don't suggest whole wheat starter because that adds too much of a biological load to the starter and makes it likely you are starting a new starter rather than reviving an old one.  If you weigh ingredients, I use equal amounts of flour and water.  About 50 grams of each would be good.  (If you think that's not the same as the cup measurements, you're right.  Scoop the flour aggressively to compact it as you measure it - you should have about 60 grams each of flour and water.)  The starter should be fairly thick, like heavy cream maybe.

Cover it, 8 to 12 hours later add another 1/4 cup of water and 3/8 cup of flour.  After that, every 8 to 12 hours discard half and then feed another 1/4 cup of water and 3/8 cup of flour.

It should revive in a few days.  You're looking for a starter that will, at least, double in size between feedings (which is one reason I suggest a fairly thick starter).  If not, try with a freesh spoon of starter from the jar that you saved in the fridge.

Prevention is the best thing here.  Refrigerated starters last better if -

• you feed the starter just before you put in into the fridge
• you make the starter quite thick - like 60% to 50% hydration and
• you take it out and refresh if from time to time - no less than every 2 months or so.

Hope that helps!

Mike