I did found that my total post has decreased a bit in the last days, i had thinked all post would keep with me and wouldnt decrease, soo my question is some thread got locked, it will be deleted and i will loose any post i had made into those ?
Locked thread, no. Posts are still counted and can be converted into activity. However if the thread is deleted by moderators, then I think the posts will get deleted and your activity may decrease depending on your situation.