I managed to damage the boot sector of my pen drive. What I want to do is to repair it faster without reformating and installing everything all over again - too slow. So can I repair the boot sector of the pen drive? I already tested that installing win xp is ok and Hiren's boot work without a problem. I recovered the files in the main dir like "bootmgr", "grldr", menu.lst, windefault and etc. If I try to install Win 7 it gives error "The boot selection failed because a required boot device is inaccessible" or something like that. The same error happens if the internal HDD don't have any drivers I think but this is not the case. This problem started after using auto repair option from a boot cd to repair Win 7 OS while the usb pen drive was inside - stupid me ... Problem solved copying my backup folder "boot". There is a file "bcd" which happened to be like 5-6 kb while the original backup file was around 256 kb .