Welcome to the Q&A Forum

Thanks a lot Jane

thank you Omid. Shirazi for your precious help

This is probably the extent of the answer I can give you in Q&A. I would look at when your traffic dropped, and attempt to line that up the Algorithm History. If the date of your traffic drop lines up with a Penguin or Panda date, that's a pretty clear sign. There are some great resources linked to on that same algorithm history to help you. If you HAVE been hit by Penguin (for the links), it sounds like you're doing all the right things. The process is usually disavow then reconsider, but where you haven't received a message that's probably not necessary. Just keep cleaning and keep working on gaining more legitimate visibility. Do have a look, though, and make sure it's not Panda.

thanks a lot robert for your answer