2D to 3D conversion can have several meaning, but we describe only those regarding .2d and .3d files, which is typically CAD. This can be done with programs like VersaCAD that support both of these file types.
As for the other 2D to 3D conversion possibilities, we cannot help you with them. You have to refine your search on Google and look for specifics. If you know it is a possible file conversion, use actual file extensions used by said 2D or 3D formats.