I have a toy with sound effect, when I push a button on it, it plays a sound.

The button sounds like a switch. have you measured the voltage across the switch both before and while you push it?

I want to turn this toy into a 1 minute timer, so that when i push the button on it, it will play a sound after 1 minute.

Do you want the sound to play 1 minute after you press the switch or do you want the sound to play for 1 minute after pressing the switch?

 

Thanks everyone for the help!
Finally figure out why it wasn't working. (The attached is the working circuit)
Turns out that the NPN will remain conducting once it's triggered, a 100Ohm resistor to the Emitter fixes it.