Brong switch to switch: prompt
see : Password recovery PDF

on switch:

switch: set BAUD 115200
switch: copy xmodem: flash:c2900XL-c3h2s-mz-120.5.2-XU.bin

in your terminal emulator software:

send xmodem

after succesful upload

on switch

switch: unset BAUD

or

switch: set BAUD 9600