R.java disappears after project clean

Question

After I added some .png files into my Project Workspace drawable folder I refreshed my drawable folders in Eclipse and the newly added files showed up. But when I tried to a

Answer 1

Delete your project from workspace witout source deleting and then import it into workspace.

RightClick on your Project -> Delete /Don't select "Delete project content on disk (cannot be undone)"/ -> Ok

File -> Import -> General -> Existing Projects into Workspace -> Brouse -> /Look for your workspace(!) folder/ -> Ok -> /your cleaned project will be automatically checked/ -> Finish