Without an example of the non-working code you are using it is a little difficult to determine why it no longer works.
Using a Relative URL to access a media file like an image.
As long as the media file is being stored within the same folder (or a child folder of this folder) as the generated Story HTML file then the media file should be accessible. This is also true for HTML & media files being hosted on the same web-server.
eg. if you have the following Relative URL in your Story HTML file.
<img src="media/forest.png" />
...and if the Story HTML file (adventure.html) is being hosted within the root of your web-server then the file structure should look something like the following:
... and you should be able to directly access the media in your web-browser using a URL like the follow: