Models being turned inside out!

[Nicokick]

hi, i've got another small problem, i'm trying to copy a model and mirror it (simply using clone, then mirror>mirror X in vertex modify), but doing so turns my model inside out!
Or at lest that's what i think, the textures are only visible from inside, but the face turns invisible when watched from the outside.
And it doesent help making the material twosided.
What do i do?

 

[Mechanical Man]

Which program?

 

[Nicokick]

Which program?

Oinkerwinkles Vertex modify.

 

[D a w n]

you will have to recalculate all normals, but please backup your model first.

 

[skrab]

or simply use flip in 3ds max =P

 

[Nicokick]

or simply use flip in 3ds max =P

Sorry, but i'm a poor student and thus cant affort afford it.
I do have a downloaded version, but it doesent work properly. It freaks in more ways than i thought possible.

 

[Nicokick]

you will have to recalculate all normals, but please backup your model first.

I tried using the "recalculate normals"option in the menu, but that just did nothing.