asins Creed 2 glitch??? now all my progress was a waste...?

So have been playing asins Creed 2 on my PS3 and have come to a point where i am unable to progress anymore because of a stupid glitch... or so i am convinsed its a glitch. DNA sequence 3- Exit the Son trophy did not appear in my trophy gallery however i am now far past DNA sequence 3 and am back at the villia with the codex room blocked off because of an "incomplete" memory file... i have 29/30 codex pages... and cannot find the last one and i am sure that it has something to do with DNA #3 not regestering as completed... I hate using cheats... but is there a cheat for PS3 that gives Ezio all the codex pages???