Photoshop Image Manipulation

Photoshop image manipulation Please read requirements closely - NO design work needed - I have a very large image that is composed of thousands of smaller images. The smaller images are all square, the vast majority are 512px X 512px with some at 256px X 256px. The squares were downloaded from the source but are in no particular order so it is very similar to assembling a puzzle except every piece is square. Each section of the larger image is divided into approximately 500 pieces in its own folder, thre are 142 folders in all. I need someone efficient in photoshop or other jpg (raster/bitmap) editing software (NOT CorelDraw or Illustrator - need RASTER image program) that can take each folder, assemble the individual pieces into one image, and return the photoshop file into the same folder. I do not want any changes in the individual pieces, no change in resolution or size and each piece must be assembled as it was originally, each piece meets each other, no over lap and no gaps. This is not a drawing or graphics request although if you understand graphics it will make it easier. Just need someone to take all the pieces that are in folders, assemble them into the larger image and save that photoshop file. Please post your questions and interest for more details in messages. Thank you for considering this request.