I can't say I know the solution to your problem. For sure you need both voices installed and properly selected (the FROM/TO voices) if you want it to speak words and phrased. If I recall correctly, there is also a dictoionary file saved somewhere on the 755. Perhaps you have a trial version of the Language Guide and the update detected that it as expired. The Language Guide shipped in a new 755 was only a trial/sample and you had to purchase the real/full product from Garmin.

You might try putting the old "garminDevice.xml" back and see if it it starts to work. You might also look around the settings screen(s), there may be a separate audio enable in the mixer for that App.

Let me just offer a piece of personal opinion. I have 3 - 755's and I've had them for years and still like them very much. However, from the beginning I felt the Language Guide was total junk and deleted everything that had anything to do with it so I can't test it for you. I'd say unless you really need it, don't waste your time trying to fix it.

The reason for so many files being replaced by the web updater is not unusual. It was probably a bunch of updates and addition to the various language files. Perhaps the previous owner deleted everything he/she didn't want to free up some internal memory. In my own devices I've deleted every file having to do with any other language except english as that's the only language I needed/wanted. If you clean out all the extra language stuff (voice files, text files, traffic files, etc) you can eliminate a huge number of large unnecessary files.