It sounds like you've been sent attachments which your computer doesn't recognise as valid file types. That usually occurs when there's no program available on your computer which can open them.
For example, if someone sent you a file with a .docx file extension (which is used by the more recent versions of Word) and you'd only got an old version of Word on your computer, the file would not be recognised. Similarly, if someone sent you a file with a .psd file extension (which is the default extension used by Photoshop), and you'd not got Photoshop - or a compatible program - on your computer, you'd be unable to view it.
We need to know the file extension which has been used. If it's visible to you (e.g. 'wedding.psd'), simply tell us what it is. If it's not visible, save the attachments to your desktop, then right-click on each of them, selecting 'Properties'.
Once we know the file extension(s), we'll be able to suggest a free program which can open them or, if such a program isn't available, suggest what your correspondent needs to do in order to send you usable files. (e.g. by re-saving a .psd Photoshop document as a .jpg file).
Chris