ABB IRB6660 Need Backup

What robot controller version? Just putting any backup in there can cause system failure and more problems that you cannot fix.

You do not have any backups at all? Are there some stored in the controller? If not, you would be best served to contact ABB support with the serial number to request the proper keystring. It will enable you to correctly build that system, with all the options that it ought to have. For example, the correct fieldbus interface. Is it in system failure or just will not boot?

it is strange that the system was lost.

Was the robot working or were you doing some particular operation?

however with rw 5.xx you can generate a system in robot studio, you just need to have the activation key which is normally written on a sheet inside the controller.

Isn't the key also in a normal backup? In the files system.xml or keystr.id.