I was wondering if the old:
Unlock Special Weapons (Version 1.0.0 only)
Locate the file "unlocks.py" located in <Drive Letter>Program Files\EA GAMES\Battlefield 2\python\bf2\stats (or whereever you installed Battlefield 2, in the folders \python\bf2\stats), and open "unlocks.py" with Notepad.
(Before you open unlocks.py, you should make a backup of the file "unlocks.py" (just copy and paste the file) and rename the file to unlocks1.py)
Now you should see a whole bunch of codes. Press CTRL+F and find the word "defaultunlocks" (without the quotations).
this should highlight the line of code
defaultUnlocks = [0, 0, 0, 0, 0, 0, 0]
change all the "0"s to "1"s, so it looks like
defaultUnlocks = [1, 1, 1, 1, 1, 1, 1]
and now press CTRL+S to save.
Note: this only works for single player, this trick works for multiplayer, however, EA Games will ban your CD-Key for a week if they discover you are using this for multiplayer. So just replace the unaltered backup file of "unlocks.py" for multiplayer and vice versa