When looking for the pages of the opus in the mission Impatience of a Saint I was looking at a walk through to find the pages that I was having trouble with, when I saw that page 6 was in a building I had already been in, so I went back and looked at where it is supposed to be and i notice that I killed something and it melted on top of it so now I can not get though I can see it I have tried eveything in my abilities to get it and I can't, so now what am I supposed to do?

Try telekinesis?

This has also happened to me, and telekinesis does not work because it is completely covered the opus