can flour go bad in time?
if so,how long can you keep it

i am asking because i found a bag of flour dated last year
do you think it is still good?

Yep, it sure can. Whole wheat flour will begin to turn rancid in as few as 30 days when stored at room temperature. White flour won’t turn rancid after 30 days, but it will increase in likely hood of insect infestation. After a year of room temperature storage, it would almost be a given that the flour was infested to some extent. The only exception to this would be if the flour was stored in the cooler or in the freezer. When stored in the cooler, the flour should keep for up to 6 months, and when stored in the freezer, it should go for a year.
In addition to insect issues, the flour will continue to naturally oxidize, that is, to become stronger. The dough that is made from the old flour would be expected to show signs of more memory characteristics (shrinkage) than a dough made with a fresh flour.
Tom Lehmann/The Dough Doctor