I have blundered and deleted the wrong file from the esxi data store.
Now what I have is a [MyMachineName]-000002-delta.vmdk and I just need to get 1 or 2 important files off it.
Is this possible? I tried mounting it directly and that didn't work.
Am I completely out of luck?
You can't do that, it's just the difference blocks, there won't be any actual readable files on there at all, even if you could mount it, which you can't because it's not a file system. Just restore from last backup.