what is contained in a .pcb file and can you generate project file/ schematic file out of it?

Hello all,

I am new to PADS software and only has a bit experience in the PCB Design.

I have a .pcb file which I could open by using the PADs Viewer, and when I tried using the PADS designer to open nothing happens. it just a blank white page and no error poped up. I am wondering what is included in the .pcb file.

for example, if I got and need to continue a project from the others, there is something more than a .pcb file I need to get correct? or is there a way to check if the .pcb file can work backward to regenerate the schematic file and the project file? i.e. if I need to move a component around, the viewer would say it is locked or protected parts, and I tried to open the file with the designer nothing happened. what is the proper way to adjust the prints (Labels on the actual PCB) and moving the components?

Thank you