thanks for your reply.
My goal is to displace face 2 in xoy place while face 1 is FIXED then 'BLOCK' the configuration that I get [call it configuration 1].
On configuration1, I want to apply a displacement along z on face 2 while face 1 is FREE.
I tried the way you said (activating and de-activating) but unfortunately it didn't work. The problem is that just as u said, the body goes back to its original undeformed position when I deactivate fixing face 1. That's why I used command APDL to 'block' the body in the deformed position and it worked just fine. The problem is, in step 3 [when I want to displace face 2 in z direction while face 1 is free to move in all directions], it's considering always that face1 is fixed although I have no constraint that says so.