Assuming that you have the mass and age of a star, can you determine the most likely current class? I am asking for the purposes of generating realistic stars.  Assuming that you have the inputs of the mass of a star, and its age, is there any method for determining its class and state?
 A: 
The Herzsprung-Russell diagram, plotting luminosity against color.
I think/hope this picture might answer your question. Class is listed at the top horizontal axis but I am not sure what you mean by "state", I am guessing you mean red giant, white dwarf etc.
For main sequence stars, the line running right to left,  bottom to top,   the luminosity mass relation is show below. As the stars age,  depending on their mass, they go off the main sequence
For red giants and white dwarves, this relation below is not valid. 
A white dwarf is formed when a low-mass star has exhausted all its central nuclear fuel and lost its outer layers as a planetary nebula.
A red giant is a luminous giant star of low or intermediate mass (roughly 0.3–8 solar masses  in a late phase of stellar evolution. The outer atmosphere is inflated and tenuous, making the radius large and the surface temperature as low as 5,000 K and lower.
The main sequence  relationship is represented by the equation:
${\displaystyle {\frac {L}{L_{\odot }}}=\left({\frac {M}{M_{\odot }}}\right)^{a}}$
where $L_⊙$ and $M_⊙$ are the luminosity and mass of the Sun and 1 < a < 6.1 The value a = 3.5 is commonly used for main-sequence stars.
