How to recover files from a hard drive that had lost partition info? I was unable to mount the HD under Windows nor Ubuntu.
You could use TestDisk to recover the partitions and then all the files. Just follow the Step By Step guide about searching and saving partition information.
The only straight forward software to recover files from deleted partitions I know of is R-Studio but it's a commercial software. It's search for files works cross file system that means as long as the file is recoverable it will be listed no matter if it was on a FAT32, NTFS or EXT3 partition.