Axis of Symmetry

Hi, I'm new to modeling and have a 3d scan of a face that I'm working on, however when I made the scan the axis of symmetry came out weird and I just want to cut the face in half and mirror the side that I like.

Unfortunately I have had no luck in my research on how to change the axis of symmetry (when imported the front of the model is the side of the face).

Could someone please tell me how to change the axis of symmetry so that I can orient it to align with the front of the face?

I have access to 3ds Max 2011, Blender, MeshMixer, Sculptris, DAVID Laserscanner's Shapefusion, Wings3D, ZBrush and I can acquire access to whatever other program there is out there if you can only tell me what to do in that specific program.

Yes I'm desperate, thanks in advance!

If you will use max and you want a half of this face then you should have your pivot point in the center of your model. If you haven't, then you can simply go to right panel > Hierarchy > Affect Pivot Only and then click Center to Object button. After that just center your object in space, cut out the half you don't want and use Symetry modifier. If Symetry doesn't work then just checking Flip in modifier options should help. Eventually if there are still problems you may need to manually center Mirror position of Symetry modifier. I hope I helped

You helped very much so, thank you!