I have Sony walkman NWZ-B135F MP3,Walkman well. when i power on the player it says boot error and immediate shutdown..........

Had the same problem and fixed it, was a bit tricky.
first download the following two firmware update files:
http://www.sony.co.uk/support/en/product/NWD-B103/downloads/FRM_NWD_B10x
and
http://www.sony.co.uk/support/en/product/NWZ-B135/downloads/FRM_NWZ_B13x_f

disconnect the walkman from the computer
press the reset button
start the first firmware update (NWD-B100_V1_3.exe)
press the vol- button on the walkman and keep it pressed while you insert it into the usb port and still keep it pressed until the firmware update program recognizes the walkman
check the "format device" (or something with format) checkbox
klick "Start" wait until the program says "Finished"
Close the update program
then start the second firmware update program (NWZ-B130_V1_01.exe)
klick "Start" wailt until the program says "Finished"
Close the update program
now the walkman should be empty, formatted and working again.

If you have the initial executing files that were on your mp3 when you bye,

Format your Mp3 on PC by FAT32 format and copy those on your Mp3 player folder

if not , mail me : [email protected]