This zipped copy of the RESISTANCE.SQC file, which OFP player Snake Man forwarded to me, was taken from his completed Resistance campaign. Using it, you can revert back to any campaign mission you want to. Of course, the file reflects someone else's campaign scores.
Your existing RESISTANCE.SQC file can be found on your PC in the following location:
Before replacing your old copy with the new one, make a backup copy of your old RESISTANCE.SQC file. Then simply unzip the downloaded file and replace as a new copy of the RESISTANCE.SQC file.
When you go back into the OFP Campaign Book, you will now see a complete list of all the Resistance campaign missions available. You can now play any of them at will. However, by doing so you will spoil for yourself the campaign story and sequence. My personal suggestion to everyone is to select the mission after the last one you successfully played and click on REVERT. This will return you back to where you last left off in the campaign and require you to successfully complete each mission in order to advance in the campaign.