"That" – alternatives could be "it", "that", "something", "the matter". Hmm, "it" is straightforward. Maybe that? But "that" is the original, so perhaps include it as one of the options. So it.
Putting it all together, the sentence becomes: "That" – alternatives could be "it", "that", "something",
"With" – with works.
myself am unable to help regarding that. "That" – alternatives could be "it"
So revising the first word: one? Hmm, "One cannot help with that." That sounds more formal but is grammatically correct. "One can’t help with that." is acceptable. So maybe the revised alternatives for "I" are better as we. Let me adjust that. "the matter". Hmm

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