This script will make iTunes play regardless of its current state. From the AppleScript Users List.
OS version: OS X
tell application "iTunes"
set myState to player state
if myState is playing then
pause
return "Pause"
else if myState is paused then
play
return "Play"
else if myState is stopped then
play
return "Play"
else
resume
return "Resume"
end if
end tell