Did the sender send a plain text message with pictures attached? If so, why
can't you see them when you open them? You give too little information to
know why you see what you see. No version of Outlook, no account type, no
symptoms of any kind. We can't read your mind.
The sender gets to choose the format, not the recipient. Tell the sender
you prefer they send you HTML-formatted e-mails (despite that the same
pictures are still available in their plain-text version). They might
listen, they might not. Their choice.