I can not play my old game on my new computer with the NEW or OLD launcher

I have an old version of your game that I have enjoyed playing for years.  I do not want to lose all that I have done.  I have a new computer and I tried to load the old game onto it and it would not play so I loaded the new launcher on it.  The new launcher will not find the old files so that I can play my saved game that I have been playing for years.