(btw, you say that all plugins are in fact there, but I don’t see “Intakt”)
One possible reason… have you updated those Instruments since you last saved the project that you are now trying to open?
You could at least try the following (but no guarantees that it will solve some of the problems)…
In that “Missing Ports” dialog, in the “Mapped ports” column, try to re-assign the desired instruments.
Do you still have Cubase 5 available? If so, does it still load ok there?
If all good so far, save Presets for each of those Instruments natively (i.e. in N.I. format, not as Cubase vstpresets).
Your next recourse, in Cubase 7.5, is to replace, in the VST Instruments Rack, all the ones that show !!!Missing!!!, with the ones that do load ok (and you’ll also have to reassign them in the Project Tracklist), then if you have been successful in saving those N.I. presets, try to reload them into the newly-loaded instruments. Otherwise, you are going to have to try to recreate all those patches manually .