Is the .png included in the solution?
When you hit the "play" button your essentially starting up a new website ( localhost:2383 ) so if its not in the solution it won't be copied over to the new, temporary, website that the debugger attaches too.
If this is the problem a quick fix is to hit the "Show all Files" button on the top of your solution explorer, this will show all the files in that folder on your hard drive. Then right click on the .png you want to include and hit "Include in Project".
Based on your comment your only solution is to actually create an IIS site for your solution with the root dir the same as your web project. Then in the project properties you'll have to tell the debugger to attach to your local IIS instead of visual studios. Not sure the exact click path, right click on your project and go to properties, look for debugging options.