I have a major problem. I cannot advance the quest, Liberation of Skyrim, after taking Whiterun becuase Galmar attacks me on sight for no reason. I have concluded I have no bounty, I have tried every console command I know of, resetai, disable/enable. I don't know how to get him to stop attacking me so I can talk to him to advance the questline.

You should consider to reload a previous save.

Have any mod's installed ???

I have alot of mods, but they shouldn't be interfereing with them at all. He was fine up to this point.