For the Start menu, I assume you're talking about the taskbar that appears on the bottom of the screen. Press the Windows button on the keyboard (usually located between the Ctrl and Alt button on the left hand side).Right-click on the Start button. Click on the Taskbar tab and check the box that says "Lock the taskbar". Your taskbar should return to your desktop.
Wallpaper (desktop image)
Right click on a blank space anywhere on the desktop. Click on graphics properties. You should see a window with your Wallpaper previewed in the top window. Click in the Settings. There should be a setting for "Stretch". Select Stretch and your desktop should return to normal.
In Vista: Right click on a blank space on the desktop, click personalize/display settings/advanced settings Click on your graphics card if available or graphics properties. You're looking for Aspect Ratio options From here you will see a setting with 2 options
- Maintain aspect ratio
- Full screen (no border)
Depending on your graphics card, this process may differ slightly, but the setting you need is Aspect Ratio
I hope this answers your questions. Best of luck.