Unanswered filament not being extruded

OK, I did a good print fairly large and all came out good. started a new print this morning, same filament, got as far as the first couple of layers done then the filament stopped advancing. retracted the filament, reloaded it. I was able to get filament out of the extruder by hand, but when I tried to extrude it with the gears I got nothing, when I extract the filament, the last little bit is stringy from the extruder. cleaned the drive gear, still doing the same thing