Can't find app on iPhone...

I have lost my Mail app, the default one. I recently tried the iGmail app and thus moved my Mail app into one of my hidden iPhone app screens. I have now deleted the iGmail one and I can't find the Mail one. When I use the finder on my iPhone it pops up, but it won't show in any of my screens, especially when I look while my phone is connected to iTunes. I want to move it back to my Home screen. Does anyone know what has happened here? So confused.

Thanks
Greg