Why your circuit does not work? Because the battery is run out. These low voltage indicator circuits may helpful for you. If you can know before and change a new one right now. It makes you not have to waste time when using those projects.
The simple low voltage tester circuit using LM339,can use Battery voltage monitor for voltage sources that problems, by LED display and alarm sound.
This fine 1.5V battery tester circuit using LM324, Can measure the voltage of the 1.5V battery AA or AAA. As decimal point. Easy to use by LEDs display
Simple battery status monitor circuit using IC-7555 or low power LED flasher by ICM7555, need to use LED display status of the battery 6V-12V
If you want to teach kids to learn simple LED circuit. This is one of good circuit. It is the Simplest On-Off battery indicator using two LEDs.