Hoping for help - factory reset

[Guest SarahD]

So my SD card has died the death, and taken with it a whole bunch of data caches and settings. Tried everything to save it, but even after booting without the card in, all the apps (including launch screen, messages, market etc.) are stopping and being force closed. It got to the point where my laptop isn't recognising the phone at all, so I decided to just go all out and factory reset to start over, but I didn't do the original install, unlock and firmware stuff, so I have no idea what to do. Any suggestions as to the best (by which I mean least buggy, I'm not a massive modding fan) firmware and setup options, and help on how to set it all up?