Use a trainer in barracks and give yourself another token, create another class and then see if scavanger is available then, if not try checking your files on steam
(Go into steam - right click Call of duty 3: multiplayer, from the drop down menu choose - properties - then - local files - then VERIFY INTEGRITY OF GAME CACHE, steam will check your file for errors and download any missing/corrupted files -OK -now do the same - but choose DEFRAGMENT CACHE FILES - now try game again and see what happens)
If that dont work - try a trainer to unlock all 'pro perks' - im almost sure you dont have access to create a class till level 4 - after that you should have access to any classes/perks you carried through prestige
hopefully this helps - defrag and integrity checks helped me before
if Ive helped REP ME and THANKS,
CHEERS