Help request for restarting Total War Medieval 2 Teutonic Campaign

[TRRoosevelt]

All,

I'm new to TWC and the Total War community, am a technical luddite and use a Mac.

I recently purchased Total War Medieval 2 and wanted to play as the Mongols in Teutonic.

I watched a YouTube video that showed me how to do this.

I opened the descr_strat.txt file and edited using text editor.

I cut "mongols" from unplayable factions and pasted it under playable factions.

When I went to play the game, the Mongols did now show up as a playable faction and the game wouldn't work no matter what faction I chose if I clicked on "Teutonic Campaign."

I reopened the text editor and switched "mongols" back to unplayable factions, but the game still won't work.

I've copied the text editor file and attached it.

What do I do to make the game work again? And, what am I doing wrong to enable the Mongols as a playable faction?

Thanks in advance for all your time and help.