When I was bottling, occaisionally the yeast would drop out of suspension to soon to finish carbing the beer.
So, after a couple of episodes of this, I started, after a few days, inverting the bottles, giving them a gentle shake, and putting them back in the box.
As suggested earlier, you can experiment with a couple of bottles by opening and inserting a carb tab and waiting another week to see what happens.
I would resuspend the yeast, put the bottles where it is 70-75 degrees and wait a week.