Stuck in the cut scene in Speaking With Silence quest, help plz!

[Tyrania]

So im doing this quest : speaking with silence and I've worked my way into the Veil Sanctum to the puzzle door: after coming back, and dismissing my follower and a few reloadings he opened the puzzle door, but after i enter ( with weapon drawn) Karliah shoots me with the poised arrow, i fall down and Mercer Frey comes in and just stands there doing nothing, the cut scene lasts forever and i cant get up! i tried waiting function but it doesn't work, i tried becoming a werewolf but right after i come in i get shot and it glitches anyways, by the way: i have Serana the vampire following me to take her home, but she cant get in with me inside the sanctum, im on XBOX 360. plz help and dont mind my English, it's my 3rd language guys.

 

[M'aiqaelF]

I'm not sure how to fix this problem exactly. Are you able to go back to a previous save file?

 

[Tyrania]

I'm not sure how to fix this problem exactly. Are you able to go back to a previous save file?

I tried, i even did it all over again and it didnt work, reloading only worked for me once when he had to open the puzzle door..otherwise the cut scene after entering the puzzle door still wont trigger