Q: i bought an iphone 4s with no icloud password

i have a problem >>>
recently i bought iphone 4s 16 gb with no icloud password and who sell me it. not back the iphone . i have a problem with my iphone have no password for icloud so every second ask me write the icloud password .

i am tired about it .. lose my money and my iphone not work as i like

please i can't rest icloud
how can i make my iphone working with no sad time help me plz

any info plz ask  ....need your help apple admins to take out the icloud account and clear ...