Any ideas?

The quest name is Hired muscle, pretty early in the Companion quest line. It tells me to beat up an NPC named Javier at Chillfurrow farm. Unfortunately there is no one there by that name and there doesn't seem to be any record of an NPC by that name on any skyrim databases.

Is there a command i can use to mark it as complete and continue the quest line?

The command (and stages) are listed at the bottom of http://www.uesp.net/wiki/Skyrim:Hired_Muscle

Awesome thanks