Per default INTERACT creates a backup file for every data file you work with. This happens in a certain time interval.
To check if this feature is activated or to change the backup interval:
▪Go to General - Program - Settings 
- Backup and change the settings as desired.
Those backup files are created in the user directory of INTERACT: (..\Mangold INTERACT Data\AutoBck\) and carry the suffix *.ab~.
The files are overwritten every so many minutes as entered in this dialog.
INTERACT automatically deletes those backup files as soon as you exit the program.
System crash
Whenever INTERACT is not closed properly (e.g. due to a system crash) those backup files are not deleted. The next time INTERACT is started, all backup files found inside the AutoBck folder are restored and opened automatically.
Those restored Documents are all titled Recovered: < original name> .
If you want to use the backup file instead of the (maybe not existing) original file:
▪Click Start - Current Document - Save 
> Save as..., to save the recovered file in an other location.