How to recover my password

I have forgotten my login password of my Iphone. After several trial to login but it was not successful and my phone is being blocked and request to connect to itune. When I connect it to the itune , the itune asked to response on my phone. I cant do it because my phone is totally disabled . What should I do to recover my login password ? or to restart my phone. I usual to sync my iphone through icloud at present. I still see I have sync this phone with my laptop. I have the phone name and serial numner. it should be able to reset somehow from the password issue. Please advise