I bought a flash drive, connected to computer, I opened properties and it said that it was in fat32. I decided to format to ntfs. As usual I went to My computer - Device Manager - Properties - Policies and clicked on Optimize for perfomance. Right after that computer suddenly freezed, and didn't respond. I decided to unplug that flash drive manualy. Then I plugged in again and now it's not seen neither in My Computer nor in Device Manager. So what happened to it? How to restore it so that it can be seen again?