Too late to fix?

I have a six gallon batch that I bottled about four months ago. After a month of letting the beer mature in the bottles, I tried it out. Not good. It was flat, no head whatsoever. There was enough carbonation that you could hear when you open the bottle cap, but none in the beer. It had a flat slimy after taste too. Someone suggested adding up to 3/4 tsp of priming sugar and recapping the bottles to try again. Is it too late to do this? I wasn't sure if there would be enough living yeast left to recarbonate.

Assuming you gave these bottles a month at 70 F, I'd suggest using carbonation tablets. They provide a more controllable level of carbonation. Then leave your bottles for another three weeks to a month at 70 F.

Yeah, they were between 70-75 degrees the whole time. Before I went to the trouble I just wanted to make sure there was hope so I wouldn't waste my time. Kegging is looking much easier. If only I had space for a kegerator.

One reason I have found for inconsistent carbonation is a failing to give a gentle stir to the finished primed beer before bottling. Now I rack onto the dextrose-water combination and give a gentle stir with the sanitized racking cane.

I mixed my priming sugar (3/4 cup for 6 gallon batch per instructions) in a bottling bucked before I filled my bottles.