I was unable to find someone with the same issue so I am posting it here in case it happens to anyone else.
It appears something happen to a saved excel file because when I open the file it says "Cant find project or library" but after pressing OK I open to the vb window and I can see all my modules listed. However when I try to click on any module or worksheet to see the code all that comes up is an empty white box (no code). See attached 'no vb showing' image of what I mean. Note there is no option to compile code either.
Then when I close the file it says the missing library message again and excel crashes (see excel stop working file attached)
I will continue to try and find a solution, just wondering if this has happened to anyone else?