How to update iPhone 3gs without computer?

Okay, so i was getting ringtones on my iphone 3g, but it said i must update to the latest version of ios. My mac is updated, so i was going to use my computer but i lost my usb!
so i have Wi-Fi on my phone, but is there any way i can do it from my phone?

I think you can only use Wi-Fi if you have os 5 or higher

What version of ios are you currently on? If your on 5 then you can do it from settings menu on your phone. If your on old ios then you have to connect to a computer x

There's no way you can't update iphone without usb to plug in computer srry
but you can buy another usb for lke $5 in apple store i think