I've restored quite a few photos to my older posts - I usually wait until I want to refer to one for some reason or someone else asks a question. 

You need to find the box marked 'Entry Actions' at the bottom of your original post then select 'Edit' in the list that appears. 

You will see your original entry with 'place holders' for the original pictures and a box at the bottom for adding new images. 

Assuming you still have the originals on your computer, drag and drop them into the box at the bottom,  where they will add to the list of missing images. 

Then you have to click on the place where you want an image to appear in the text and then click 'insert' just below the relevant image.  Repeat until all your new images re in their correct places and finally delete all the 'dead' images by clicking the 'X' by each image. 

You will also have to say which 'group' your post should be in and a reason for editing.  If you then click to save the new version, it should replace the original version.  I

think the bug that caused posts to appear with the current date has gone but it thts is a problem, you will need to re-enter the date when the post was first made before saving..