sorry if I'm being a noob but a while ago I jailbreaked my 3GS on iOS 4.2.1. At the time you could only tethered boot it and you had to install the ipad baseband drivers for it to work (not sure if its the same now).
this all worked fine. however, i lent my phone to someone who decided to 'erase all settings and data' (or whatever the setting is) and then it would boot. looked it up and this apparently deletes the OS so tried to do that but kept getting errors in itunes (more googling). finally i think i have now got 4.2.1 back on by using tinyumbrella running in the background. however it will still not boot tethered, it just sits at the pineapple bit.
any ideas? i would like to just put it back to standard OS but dont think i can now that it has the ipad drivers...
thanks in advance