Forgot my iphone 4 passcode

Me and my boyfriend were messing with eachother today and I changed the passcode on his iphone (we both know eachothers codes.) In fear of him getting revenge and changing my passcode, I changed mine too so he couldnt get into it. Ironically I forgot what I had changed mine to, but remembered what I changed his to! I'm very frustrated, I don't want to restore it and have All of my files etc.deleted! Is there any way that I can unlock it without having all of my stuff deleted?

Take it to the apple store

You MIGHT be able to plug it into iTunes on your computer and transfer the files, music etc.

About iPhone Passcodes

The exact behavior of the iPhone depends on its configuration when one forgets the passcode. By default, there's not a passcode at all. However, Apple notes the following regarding forgotten passcodes:

If you repeatedly enter the wrong passcode, your iPhone will be disabled for longer intervals before you can try again. After too many unsuccessful attempts, you won't be able to try again until you connect it to the computer with which you last synced it.
Note: You can configure your device to erase itself after ten consecutive incorrect password attempts. This setting is off by default. It can be turned on by tapping Settings > General > Passcode Lock.
If you can't remember the passcode, you will need to restore your device using the computer with which you last synced it. This allows you to reset your passcode and resync the data from the device (or restore from a backup). If you restore on a different computer that was never synced with the device, you will be able to unlock the device for use and remove the passcode, but your data will not be present.
How to Unlock iPhone Passcodes

If you have forgotten the passcode on your iPhone, you will have to restore the device.

To restore your iPhone -- which deletes all of your data (songs, photos, videos, apps, and so on) on the iPhone use the following directions. Be absolutely sure that you have backed up the content on your iPhone before restoring it.

Apple's official instructions to restore an iPhone are:

1. Connect iPhone to your computer.
2.In iTunes, select iPhone in the Devices list, then click Summary at the top of the screen.
3. Click "Check for Update." iTunes tells you if there's a newer version of the iPhone software available.
4. Click Restore. Follow the onscreen instructions to complete the restore process. When restoring, it is recommended that you back up iPhone when prompted. When the iPhone software has been restored, you can either set it up as a new iPhone, or restore your music, videos, app data, and other content from a backup.
Please also note that Apple representatives can't unlock an iPhone for you without restoring the iPhone, which will erase everything on it.