Lazarus is NOT a virus or a trojan, as people think or believe.

In the first Amiga OS releases, Commodore included a standard floppy disk recovery utility called 'DiskDoctor'. It's purpose was to recover files from mangled floppy disks. Unfortunately, this utility worked only with AmigaDOS standard disks. A major fault was that it did not save the recovered data on different disks, rather it saved the info on the original and performed it's operations directly on the original. It wrote on original disks and destroyed non-AmigaDOS disks (mainly autobooting games) by overwriting their bootblock. 'DiskDoctor' renamed recovered disks to 'Lazarus'.

These features were undocumented and led to an Amiga users believeing that there was a computer virus with the name 'Lazarus' Virus, whose final purpose was to make disks unreadable and renaming it with that name. Third-party developers released data recovery programs such as DiskSalv, which was more often used to validate Amiga filesystems on hard disk partitions.

You should delete 'DiskDoctor' from your disk and never use it again. Try and use DiskSalv instead.