My web site was firs rank in gogle some results but now my web site on last rank some websites got content from me but there are first now i didnt understand why this do?
Some time it happen. May be it would be Google Dance or you have done some wrong things for your site. If you are doing quality work for your site than don't worry your keyword will definitely get on top. Just do the quality work and wait for some time.
This morning google added some sort of penalties or made some algo changes. One of my websites just dissapeared from first page. Same thing happened in november with another page of mine wich came back to normal few days ago.
Some thing like happened with one of my new site was ranked in first page but previous week it just go to last page , I don't know why it will happened
I'm having this problem too. Google must be doing some changes. Things should return to normal after a while.
may be the links that you got for the particular keywords, has been removed or else the competition of the keyword has been increased.