LED resistor calculator wrong?
Ok, first let's check the resistor value.  We'll do the maths so you never need trust a random website again:

$$
V_{DROP} = V_{IN}-V_{LED} = 12 - 2 = 10V
$$
$$
R=\frac{V_{DROP}}{I_{LED}} = \frac{10}{0.03} = 333.\dot{3}
$$
So that all looks OK.

So why isn't it working?  Well, some possibilities:


The LED is connected backwards.  LEDs are polarized devices and have to be connected the right way around.  Look for a flat edge to the rim of the LED which denotes the negative (cathode) connection. Also LEDs often have leads of different lengths. The longer is normally positive (anode).
You have blown the LED.  Accidentally putting 12V through the LED will pretty much instantly kill it.