Let me brief it more:
I was only using itunes for all of my stuff (backup, restore, sync etc) and everything was going 100% fine. Sorry to say i em a new iphone user and then few days ago i read about the icloud and apple is giving 5GB free space so i realize why not i use that space too for my backup.
Then in my phone setting >>accounts>>add account i added my apple id and password soon account added in my phone. Then i go in setting>>icloud>>storage & backup>>backup (i manully backed it). for verification i went on www.icloud.com and login with my apple id and i saw my contacts on it. then i disconnected from wifi and with happy face i came into my room. other day i again connected with wifi and when i made a call to my dad huhhhh..... every contact was gone.. also nothing is showing now in www.icloud.com..
for the sake of my contacts i import them each time manually from contacts>>import sim contacts whenever i connect with wifi, because after connecting with wifi my all contacts gone nothing else.
Thats my story.
iphone 4s (ios 7.06)