Please help us to help you:
I'm assuming that you're using a web-based email service, rather than an email client. Is that correct? (i.e. to access your email account do you go to a web page or do you use a special program such as Outlook Express or Windows Live Mail?)
When you try to download attachments, what do you do? Do you left-click on a link, or right-click? What normally happens but isn't happening now? (e.g. would you normally get a 'Save as' box or would the attachment actually be displayed straight away?) . What type of attachments are you referring to? (Just documents? Just images? Something else?).
I'm sorry that there are so many questions (and, at this point, no answers) but there are lots of different ways of accessing email accounts and downloading attachments. We'll try to help as soon as we've got the relevant information.
Chris