Thank you guys for your help and advices, the issue is over now,
what I did, based on one of your advice, i swapped the two ext.s back and cancelled the message remotely on the Exten, which the message was sent to, by dialing Mes. Deact. Code + Ext Num. the MWI turned off finally, then I made another move & swap, everything back to normal.
Thank you all again and really appreciate you advices,