Dump cause of no airlock? No that would be silly. Unless the batch got infected somehow.
Its only been 3 days. There is still a bunch of Co2 still in there. My beers are still gassing off co2 a few days after fermentation completes. just throw some sanitized water solution in the air lock and you should be good to go.
I certainly wouldn't dump anything yet! The chances of it ruining your batch are actually really small, although you don't want to make the same mistake again. Fill the airlock, let the beer ferment out, take a gravity sample, and give it a taste.
Assuming you are not kidding... NO, leave it alone and don't worry about it.
I routinely use airlocks without water. The water is more a risk than anything else. Make sure you cover the airlock to keep any critters from getting in.