How to create a new accent

[Aikanár]

I am trying to fix my Third age sound and get rid of the orc accents on my Silvan elves. I changed them to English in accents and deleted the voice.dat and voice.idx files but the files don't regenerate even when I add back the unpacked files above. Any idea what my problem is there?

By default the mongols (silvan elves) are assigned to the english accent!
If this is changed, the easiest soloution is to do a new installation.
But if you want to do it without a new installation, you've to make sure that you've extracted the original Voice.idx of Third age in the first place.
Make sure you've copied the extracted Voice folder from Third_age\data\sounds\data\sounds to Third_age\data\sounds.
Place mongols in the accent English line of the descr_sounds_accents.txt and remove it from whereever it was misplaced.
Delete your Voice.idx, voice.dat, events.idx and events.dat.
Start the game = should work.

Also I have been thinking of giving them a French accent but can't open voice 3 files with the extracter mentioned above (which have the strat map voices I am looking for)

thnks

As long as you just intend to add the new accent French to the game, you just need to copy the corresponding sections of the MMII vanilla soundtext files into your corresponding soundtext files in the Third_age\data folder. You do not need to extract the vanilla voice3.idx to have them played. The game always reads from vanilla .idx files when some files are not found in the modfolder, thus the multi-localization compatibility. That said, the files have to exist in the .idx files i.e. only vanilla files.
But if you want to extract the Voice3.idx, just place all the files of the .idx extractor into your Medieval II Total War\data\sounds folder and make sure your extract_sounds.bat looks like this:

.\xidx.exe -x voice3
pause