I did all of this but it is really stressful and in half an hour I could clean only 1tile but I can see stains still .Dont't know what to do ? I am really depressed pls help me !

If it is not a natural stone tile use a vinegar/water solution to clean it.

Read this: http://www.wikihow.com/Remove-Grout-and-Cement--Spots-off-Ceramic-Tiles

Thanks for sharing useful information Connie!

I had the same problem! I used a 50/50 water/vinegar solution mopped over floor first, then scrubbed each individual tile by hand (my grout haze was reallyyyy bad), then used a steam mop and finally a normal mop.