thats basically the title. I cant use regroup on milkshape anymore. I tried uninstall then reinstall again to see if its a seting problems, but it keep the same. Any ideas?

Make sure "face" (not vertex) is selected under "select options" in the "model" tab.
Milkshape doesn't want to regroup with only vertices selected, it needs the actual faces to be selected.

It also looks like you've got "wireframe" selected for the regular view and possibly the overlay (if you need to fix this, right-click menu in 3D view, see what's ticked. "Smooth-shaded" or "textured", plus "wireframe overlay" would give you a grey/textured, smooth mesh with a wireframe overlay).

OMG, it worked! to think it was something so simple.
I was almost crying trying to join meshes in blender. Thank you very much
thanks for the wireframe tip too

It woked for me, thank you so much for help.