You workin with Sketchup? When I export my objects from Sketchup and convert them to .obj I have no textures anymore. Did you have the same problem (and maybe a solution)?
There may be two problems, with export in .obj textures save in folder with name of file, and problem may be in the model, it is need to add texture to a white side of face, if u place it on gray side, texture won't save, I have the same problem some time ago.