At different times,I tried to reformat a couple of SATA hard drives with Linux OS's on them,
with a gparted boot CD. I deleted all partitions, then on attempting to make one new partition, they both ended up unusable and fdisk reported recursive file systems - loop0 to loop18 the loops having various sizes, also being
read only. gparted would not allow any operations on the disks, I can not delete, format etc, every operation results in error messages.
Neither Windows or Linux OS's nor partition utilities such as testdisk, Paragon, HDAT2, recognize disks, though fdisk & gparted do, although they will not allow any operations on them or give them a disk name ie sda sdb etc.They are shown by fdisk as DISK /dev/loop0 7.5MiB etc to DISK /dev/loop18 2.3 MiB etc.
Later I reformatted a third SATA similar HD with the gparted CD & that formatted without prob's
I don't want to save/recover any data on the drives, I would just like to delete the loops/delete any partitions etc/format/low level format/etc the disks, just to make the drives usable again.
Has anyone, come across this problem, have any ideas on how to fix them.
I cant use any fdisk commands such as fdisk /mbr as I cant identify the drives, as sda sdb etc.
Thanks.

I've never used that one, I've always used a linux live OS that has gparted on it to do my partitioning if I am starting a new. maybe give that a shot. I've never had an issue doing it that way.
I think
manjaro, mint, and a few others have gparted in there live os.

Generally when using GParted, you should use the Device tab to create a new partition table of your choice and then try to format. Depends to a certain extent on what you had on or what you were using the Drive for. Make sure you get the correct drive if you do this.

Thanks people but these answers are really no help at all.
I really need to know how to clear the Loop Devices,
if indeed they are blocking the deletion of the partitions,
or how to delete the partitions which gparted will not
allow me to at present. Rgds.