Go to the Control Panel and there is a section within that for Clock, Language and Region (that's what it's called in Windows 8 but I think that it's the same or similar in 7).
I have an Asus too (and very good it is) - I like the larger keys and its durability (though I am not an engineer).
Re your question, bottom right of screen there should be a small display of time, volume, wifi signal etc and I have my language EN - press on that or go behind on the solid ^ cap sign, either way you can bring up your language bar and settings, click on the right, and then change to English in there.
reading your question again, you didn't install windows 7.... you simply went through the initial setup procedure when you first turned it on.
Turn the laptop on, keep tapping F8, when the startup menu comes up select repair my laptop and then select restore windows and programs to original condition. and do a destructive restore.
Doing the above will take the laptop back to it was when you took it out the box so you'll get the chance to do the initial setup again.
(if the above options don't show for you then post the exact model of the laptop)
thanks for your help nothing happened with the F8 key its a ASUS X54C notebook/pc
if i delete the windows will i be able to restore got no disc with it
Are you now able to get into the Control Panel?. If so, click onto 'Regional and Language settings' (as suggested by bibblebub) and just alter the language from the drop down menu. However, if everything is in Portuguese, you need to look for an icon in the Control Panel which is a globe of the world with a clock attached to it.