IPod touch complete restore ?

How can i restore my ipod to it's original state? I want to restore my ipod touch 4g, so it is just like the day i bought it with all factory setting and all the memory and default apps that came with it. I recently UNjailbroke it but the battery percentage on the status bar remained and as cool as it is i want to delete it and yes i have a 4g ipod touch. the battery percentage looks like this http://www.ifans.com/forums/showthread.php?t=205810 and i want to delete it. BASICALLY I WANT TO MAKE MY IPOD TOUCH 4G LIKE THE WAY APPLE SOLD IT TO ME. I want to restart fresh again. Also is it possible for an ipod to lose sound because I FEEL that my ipod touch 4g has gotten softer when it comes to sound loudness. Thanks in advance!