Its a circuit using a 555 IC with a wire from terminal 3 on the IC and a finger touching it triggers the output to a LED.
Pin 3 is the output on a standard 555. Touching it will not trigger the 555. You probably mean pin 2, do you?
To trigger the 555 you need to create a low going input voltage pulse on the trigger input. An isolated finger touch will not be able to do so. What may trigger the 555 is a connection to the 555' ground via the body's resistance and/or capacitance. This requires that circuit ground is somehow connected to your body, e.g. by using a sensor consisting of two metallic parts, one connected to pin 2, the other to ground.
Use a switch and a series resistor to simulate the trigger in this case.
Or you rely on the small rf voltage that your body picks up to trigger the 555. This works with many CMOS ICs, but the 555 requires a trigger current of 0.5 µA (0.9 µA max). If this is your triffer method, use an LMC555 (CMOS version) whichrequires a trigger current of only 10 pA.
Use a switch and a small rf voltage source to simulate the trigger in this case.
Ceterum censeo: show us your circuit diagram and the expected trigger method.