hi i am making a multiple alarm clock my problem is when i make a out put pin a6 and a7 that is not working So my guess is that there are no a6 and a7 pin is for out put
suggest me any coding issue or hardware issue
Your guess is correct. Pins A6 and A7 on the Nano can only be used as analog inputs. You can use any of the other analog pins on the Nano as digital outputs.