A: Don't do anything which may cause further corruption (including trying to initlaize, reformat, parttion, chkdsk or similar)
B: Find someone with a physical pc that still supports IDE, and try putting them in there, rather than an USB-> IDE Bridge.
C: If they still detect at a hardware level, but fail to show as valid drives, try scanning them with some _decent_ data recovery software that find damaged partitions, or recover files indpendently of the partitions.
D: If you don't mind waiting a bit, and paying postage, I'm happy to attempt to recover them for you (I live in Kapiti, so postage form Palmy should be fairly reasonable). If the drives are physically damaged it's beyond me (don't have a clean room or the specialist knowledge to rebuild them) but I know more about software recovery than many people who aren't recovery specialists.
E: Pay someone like datalab.co.nz to do a pro recovery, but be prepared to look at a bill of $1000+