Arabic Text is appearing as ??????

You need to change the encoding for the page used by asp.net:
http://msdn.microsoft.com/en-us/library/39d1w2xf.aspx

Have you configured localization in your ASP.NET application? For example, what values are set for Page.UiCulture and Culture attributes of the Page?

All cultures are Arabic Saudi Arabia and utf 8
but still the question marks are there
i followed the link sent by coehoorn also
http://msdn.microsoft.com/en-us/library/39d1w2xf.aspx

but still the problem is the same

page ui culture is also ar-sa
i tried windows-1256 and utf-8
both are not working

Try adding the language in Internet Explorer and see if that works.

Goto Tools -> Internet Options -> Languages and the Arabic language from Saudi Arabia. Close the browser and restart the IE and browse to web app again. SEe if that works. Also, once you add a language make sure that ar-sa is at the very top of the list.

Another thing to try is to check whether codepage attribute is specified in your asp.net page. If not, it should be specified in the Page Declaration as an attribute and it should be set to utf-8.

Also, to achieve the same effect you can place this in your web.config

<globalization requestEncoding="utf-8" responseEncoding="utf-8" />

i have checked the configuration
windows-1256 works with the asp.net application using MS Access on IIS6.0
But it stops working when i try to connect it to oracle database.