i forgot what the second method was, but it included using ma and then adding kau to it...
I suggested
{mi na djuno lo du'u gasnu ma kau}
or rather
{mi na djuno lo du'u mi gasnu ma kau},
meaning "I do not know what I'll do."
But as the others pointed out, something like
{mi na djuno lo du'u mi bilga ma kau}
"I don't know what I have (ought) to do/be."
may be a better translation.
You can read about {kau} at
"Indirect questions."
Matt:
"{mi na djuno du'u la'e mi bilga gasnu ma}"
i pe'i do skudji lu
mi na djuno lo du'u mi bilga gasnu ma
li'u
i ku'i preti i ja'e nitcu zo kau
"{djuno}'s x2 {du'u} frustrates me..."
ie