This is what you really need to worry about. Save the files *.wlt and *.adb. Rest you can delete and do what you want with it.
My suggestion is to do this, always fail safe. Just copy the entire standalone to a directory in C drive for example. Name it NickelNEM673
Then go into the directory and just run mon.bat. It should fire up just like that.
Now, the data directory is in yourusername\NEM. Just make sure that you copy your *.wlt and *.adb to yourusername\NEM\NCC.
If that doesn’t work, delete the accounts_cache_mainnet.json file in the yourusername\NEM\NCC directory. If that still doesn’t work, delete the file ncc.cfg in the yourusername\NEM\NCC directory.
If that still doesn’t work, delete the above two files and delete the NIS directory in the yourusername\NEM\ directory.
Run mon.bat again and you should see synchronising activities happening and the client should fire up nicely