Open electronics project file

We have a file we think is in Proteus project format but we dont use this ourselves. We would like the project opening and output to either a pdf to show the schematic circuit diagram, or perhaps converted to a freeware viewer we can read. We dont know what is in the file as we don't have the software ! It might be nothing useful. No other work is required, you just need to have Proteus or something that can read the file. I will send when project awarded.