Please post active links starting with http:// to the exact posts and/or pages the images are missing from as without them we can't even begin to help you.
If you uploaded images from your computer into your blog then they will be found in your Media Library as they will be hosted on WordPress.com servers. http://en.support.wordpress.com/media/
However, if you uploaded images from your computer onto WordPress.com servers and cannot locate them in the blog's Media Library because you deleted them we cannot help you. They are gone and you will have to upload them again.
If the missing images are ones you have linked to on some other server somewhere else online that does allow hotlinking to images such as Flickr or Photobucket, check with the image host for known issues.
If the missing images are ones you have linked to on some other server somewhere else online that does NOT allow hotlinking to images, the source site can make sure the images will not be displayed.