Flash tool Download
Tutorial

Note: If yu have ftf flash file already change the extension to.zip nd extract the file run flashtool select tools/bundle creation show the extracted folder path den follw frm 5th picture.
FTF File To Download :
http://www.mediafire.com/file/h0n065jwbbxw0mm/Xperia_X10i_3.0.1.G.0.75_lock_remove.ftf/file