You should have file in your data folder named Navdata.db3 transfer it over to the MicroRadarbox folder replacing the file of the same name in there and see if that works ok. You will however not be able to open it using SQLite as it is encrypted but you will still be able to open it using Database Explorer.
You can download a new Navdata each day through Database Explorer/Database updates. This download overwrites the previous database but if you want to keep records untouched mark them with N at Autoupdate to the extreme right of each aircraft record and then selecting the sync option Do Not update manually changed records. You would also need to untick Auto-populate Aircraft Data and Auto-Update Manually changed records in Preferences/Radarbox.
I would suggest that you save your original Navdata to a stick or safe place and then you will have a copy just in case.
Alan
