You can use a program such as gdisk (GPT fdisk
) from either Linux or Windows to manipulate your partition table (gdisk can also back up and restore the partition structure from file), but if the disk is intermittently appearing as RAW, it sounds like a hardware problem.* A partitioning tool also won't help in the case of filesystem corruption.
I don't know whether this is an external HDD or what, but I'd run a diagnostic utility to inspect its SMART attributes if you're able to. If the disk has reallocated sectors, for example, it's usually a bad sign.
Addendum: after rereading the original post, I don't think I understand question at all. If you just want to understand partition table formats for potential future troubleshooting scenarios, the above link to gdisk is a decent starting point, and it provides numerous links to external resources. As an example, here's Microsoft's Windows and GPT FAQ
(chosen because you're using Windows). The GPT format is formally defined in the UEFI specification, but unless you're suffering from a terrible bout of insomnia, it's likely you'll find other resources more useful.
* If the disk has multiple
partitions and only one of them is behaving erratically, it may be worth considering other sources of corruption, especially if there isn't any evidence of hardware failure. But after rereading the post, it sounds as though you already know the HDD is bad? And if that's the case, the partition table isn't the problem. Chkdsk won't operate on a partition marked as RAW, as you're already aware. You can try to reformat it.