Hello, I'm new here, please sorry for my english.

Well, as the title says, I just bought an already modded iPhone 2G, so I don't know how to start modding it, because I wouldn't know what the last owner did to this iPhone. The only thing I know is that the last owner told me that I shouldn't restore it via iTunes because I won't be able to use it anymore. But I would like to start modding it like it was new. I received it with cydia and many programs and games. The iPhone came with OS 3.0, and jailbroken I guess ( still noob). So is there a way to restore it without loosing its functions?

One more question, the iPhone came with NFSU, many games 3D and many programs like boss prefs. Today I was playing NFSU then I closed it, but after rebooting my iPhone I was not able to run NFSU or another game or program any more! It starts loading the game or programs, but it jumps again to home screen (home screen is right?)

Any idea? Please I hope you can help me. Thank you very much.