I missed the Protoss missions you get from the crystal in campaign mode. I did the first one but I didn't know you could go back for more. Now I have beat the campaign and I can't play them in the mission logs. Do I have to restart and do the campaign again or is there a way I can play them?
Once you beat the campaign, all you can access are the mission archives. If you never completed a mission in the first place (and thus can replay it in the archive), the only way to access the rest of the missions is over a new campaign.
Alternatively, if you have a pre-Char save of your campaign, you can load that, and go play the missions you missed (before you head off to Char, this time!)