Are there any stars that use any other elements as its fuel besides hydrogen? If not why not?
For nuclear fusion to occur, there must be a certain temperature and pressure. Generally for heavier elements, higher temperatures and pressures are needed, because the nuclei have a greater electric charge, and so more energy is needed to get them close enough together to fuse.
In the centre of a main sequence star there is hydrogen and helium. The energy released by the fusion of hydrogen prevents further collapse and so keeps the star from reaching the temperatures and pressures needed for helium fusion.
In a star like the Sun, as the amount of helium builds up, an inert core of helium forms, until (and if) it reaches the required temperature when it will start burning -- as the core has become degenerate matter at this point, the burning will increase the temperature without causing the core to expand and lower the pressure, so the core explodes. There can then be a period with shells of helium burning and hydrogen burning. By this point the star has become an "asymptotic red giant branch" star.
In stars heavier than the sun, the process can continue further with carbon, oxygen and heavier elements fusing. However the extreme temperatures at which these processes occur mean that they don't last long, and the star will eventually become unstable and blow itself apart.
So, in main sequence stars it is not hot enough to fuse other elements. In evolved giant stars it is hot enough, but it is so hot that the process doesn't last long.
Brown dwarf 'stars' are too small (13 to 80 Jupiter masses) to burn hydrogen, but burn (for awhile, there isn't much of the stuff available) deuterium. Larger (over 65 Jupiter masses) brown dwarfs can also burn lithium.