In order to be displayed online all images must be hosted online.
Where are these missing images hosted please?
When the images are in your Media Library you can insert them into your posts and they will display when browsers call for them. When an image is deleted from your Media Library it's no longer on WordPress.com servers and cannot be displayed when browsers call for it.
(1) Are these missing images found in your Media Library ie. on WordPress.com servers?
- Did your delete theme from your Media Library in which case you will have to upload theme again.
- Or are these images hosted on another site?
(2) If they are hosted on an image hosting site like Flickr or photobucket, etc. check for known issues at the image hosting site.
(3) If they are hosted on another site that does not allow hotlinking then then images may come and go, or simply disappear, or sometimes they will be linked to a stop hotlinking message.