Downloaded state is stored in another DB3.
X:\Newsbin 6 Datü>sqlite3.exe DownloadMarker.db3
SQLite version 3.7.4
Enter ".help" for instructions
Enter SQL statements terminated with a ";"
sqlite> .output dump.txt
sqlite> .dump
sqlite> .quit
X:\Newsbin 6 Datü>sqlite3 test.db3
sqlite> .read dump.txt
sqlite> .quit
This is basically how you dump and re-store a db3.
1 - I'd copy the DB3 file to another name so, you don't work on the original file
2 - Make sure you have enough disk space, the dump will be larger than the DB3
3 - I'd "read" into a dummy DB3
4 - If the dump succeeds, you can rename the DB3 to replace the one you're dumping.
There's no guarantee to how much data you can recover. If you delete the range.db3 and let Newsbin re-download the headers WITHOUT doing a "download all" there's a good chance you can fill in the missing pieces.