This is the new app that you see when you download the "back up and restore' apk file from this site through the browser of your phone, wifi or 3G.
Problem: There's no more back up and restore app from Android market after updating the firmware of Sony Xperia X10 to 2.1. How to read the file .sbf that was saved when the app "back up and restore" was used before updating the Android 1.6 to 2.1?

Steps:
1. Use "back up and restore" app on your phone, save to SD card.
2. Update the firmware of your phone through PC Companion, when you connect the phone to computer. (if you dont have the PC Companion installed,  this should be done first).
3. After installing the new firmware of your phone, connect the phone to wifi, and browse in Android market for back up and restore: nothing. Do this, on your browser, type http://www.elita-clan.com/downloads/backup_and_restore_v010935.apk. The phone will display "start downloading" while the browser will give an error message.
4. Check from your Downloads app, then install the "back up and restore" app. Give authority for the installation.
5. Now you can restore the .sbf file that you saved into the SD card and recover contacts, messages, missed calls, etc.

Sony Xperia X10 is boasting of specifications, but most  websites or blog are displaying those specifications, that I will try not to post, but rather on how to reset it to factory defaults. Doing such will make the phone brand new (firmware wise), because all your date will be lost.

I. When the phone is still accessible, go to Settings >> Privacy >> Factory Reset. You have the option to erase everything on the phone and by checking the box for SD card, it will reformat the SD card too. Not unless you dont want to reformat the SD card, dont tick the box.
II. If the phone is not accessible anymore, turn off mobile, remove battery and put it back, press and hold the left and right buttons at the bottom part of the phone then press the power button. Follow the instructions that follows. This is how to hard reset your phone.