Where did my Bios dissappear?

[dan150sp]

I recently downloaded a desktop theme (road runner theme) and then activated it. A picture used to appear instead of my bios and another pic at the time of shut down. I then deleted the desktop theme but the sad part is that the picture still remains instead of my Bios and even at shut down. How can i restore my Bios? How do i go about? Please help!