f2
F2
it's a part of system restore files
You can use a backup option, to restore from backup. Or to use one of restore points. Start->Accessories->System Tools->Backup. Or you can use the installation CD, then boot up in repair console.
Backup and Restore Utility or by System Protection
Control Panel->All Control Panel Items->Backup and Restore->Create a system repair disk.
.bkf files are backup files are are created by windows build-in backup utility NTbackup or Windows Backup and Restore (in XP). These utilities support image-based full system backups.
1. Start>All Programs>Accessories>System Tools> Backup
Automated System Recovery
You go to system restore in the backup center
Backup and restore
Windows 7 Professional and Ultimate editions have the backup feature, which, in addition to full-system Backup and Restore found in all editions, this feature provides backing up to a home or business network.
The restore process depends entirely on how the backup was created, and by what program. On my servers, using a clone of the entire system is easiest, but in industry you take a full backup and do the restore from that backup set. This can only be done after a simple install of the system to get to the point that you could do the restore.