I am always afraid of not being able to restore my phone with some sort of backup. Due to the fact that the amazing flashtool is a bit to high tech for me I was able to find a way to easy restore my device. Here is how I did this:
1: Downloade Sony Update Service from here: (Click)
2: Install it
3: Open it (it is wise to close Sony PC companion)
4: Accept the terms and contitions and click next
5: Select your device:
6: Click Next
7: Follow intstuctions on screen. If you are running the latest stock it will tell you. You can abort it and you can continue it. You also see some warnings about loosing data!!
8: After flash it will tell you to unplug device and turn it on.