I am new to blender....and just wanted to change the center of the object on it...for that i imported a .md2 file in blender....i tried to assign new center key by using the 3d cursor on blender but there is always error saying "cannot change a center of a mesh with vertex keys" if any one can help..

I believe that the vertex keys have something to do with object animations which you probably imported along with the md2. Not totally sure but they may somehow be defined relative to the object center and would break the animations if you move the center, which is probably why it's preventing you from doing so.

I'd either find out how to delete all the keys, or if you can get a different model. Try to find one that doesn't have such keys baked into it.

You can position the cursor wherever you want the centre in the 3D world then when in object mode go to "Editing" set of keys and click on "Centre Cursor"

I know that if i want to move the center of the object to the center of the mesh what i do is i use the center new in object mode in the (edit? / Transform?) menu. It recalcs the the objects center using the object verts. I hope this helps.

Edit "Reread the original post and your best bet is posted above sorry."

this all works on default cube in blender but doesn't works when I import the .md2 file...i have imported the .md2 file with animation on it....can i edit it's center or not??