convert black & white to color

I have an old program that is showing a color thumbnail of an image i was recently sent. But whenever I open it, it only shows as black and white. I thew it into photoshop with the same results, it loads as a black and white. I've been searching google but haven't found anything that tells me how I can convert it to back to color. The thumbnail of the image would seem to indicate the color information (channels) still exist. It's been awhile since I looked into the technical stuff, but I believe all digital photos these days retain their color properties, even though they're saved out of the camera as a black and white..?

Does anyone know a quick way to convert such an image, taken as a black & white, to color?