Start with the following, open Internet Explorer, go to Tools, select
Internet Options, on the General tab, click "Delete Cookies, Delete Files
(Accept the option to delete all offline content) and click Clear History,"
then try accessing the site again.
If that doesn't resolve it, assuming this is a recent issue, try using
System Restore to take you back to a time when you were able to use the site
without issue. Start\All Programs\Accessories\System Tools\System Restore.
If that doesn't resolve it, when you post back please include the following
information.
When you say it does not work anymore, what do you mean, are their error
messages, if yes, what are they? Have you made any changes recently, a
repair install of XP, a reinstall of XP, any new applications or updates you
might have installed or uninstalled.