You had me realy confused. Your header says "Software to open PDB files" but your message refer to PBD which one is it?
This is third time I am editing this reply.
I assume that PDB/PBD you referring to is a file extension. Easiest solution for you(as you are vague about the origin of the file) is to google file extensions .PBD/.PDB and choose which program you think is closest to the source(where you got it from).