What did you do to "tried a few software" - take the drive out and connect it to PC? You do realise the drive is not compatible with Windows??
I've not refreshed myself on the details of the 1100S specifically, but all the more recent Humax range encrypt the video files on disk, and some use encrypted file systems (and old models that do neither of those have custom file systems). To have any chance of success at all:
- Hope you don't have an encrypted file system;
- Hope absolutely nothing has been written to the disk since deletion;
- Identify the formatting of the disk (probably Ext3);
- Use tools specifically for the format of the disk (probably by going Linux).
Standard video file recovery tools may have a hard time identifying the blocks that make up a specific file because of the encryption, so you will probably be reduced to general undelete utilities and a great deal of manual unpicking. I'm not familiar with the general specification of Ext3, but it would not surprise me at all if it is a lot more complicated to undelete a file than the standard DOS trick of simply reinstating the file name in the FAT (as long as none of the blocks were over-written)!