S. R. Faruqi:

This theme is very common, and the honor of primacy probably has been obtained by Sa'di [in Persian]:

'Those who claim to be searching for Him are uninformed,
For he who has obtained information-- there is then no information about him.'

Even after eight hundred years, the true temper and power of Sa'di's verse have not lessened. Mir himself has often repeated the theme. In the second divan [{988,7}]:

tah be-ḳhvudī kī apnī kyā kuchh vare dharī hai
ham be-ḳhabar huʾe haiñ pahuñche kisū ḳhabar ke

[the depth of our own self-lessness-- what-all has it kept beyond us!
we have become uninformed, having arrived at some information]

In the third divan [{1283,6}]:

mat ranj kheñch mil kar hushyār mardumāñ se
us kī ḳhabar milegī ik ādh be-ḳhabar se

[don't feel sorrowful, having met with aware people
information about him/her will come from one or another uninformed one]

Certainly {988,7} is certainly peerless in its own way. Then, there's also Dard's verse:

āgāh us jahāñ se nahīñ ġhair-e be-ḳhvudāñ
jāgā vuhī idhar se jo mūñd āñkh so gayā

[no one is aware of that world except the self-less ones
only/emphatically that one is awake, who closed his eyes toward this direction and went to sleep]

In addition, see:

{178,3}.

Despite all this, in the present verse there's something that makes it distinguished among the others. At first glance, the theme is the same-- if information about you would be obtained, then from whom would it be obtained, because the one who knows you is more uninformed than all the others, so he won't tell anything to anyone.

But another reading is also that 'he who is informed/aware' is the subject, and 'only/emphatically he is uninformed' is the predicate. The mystic-knower [ʿārif] is himself uninformed in thinking that he is a mystic-knower, so how will he inform others?

A proof of this idea-- that often the mystic-knower himself is uninformed about his nearness to God-- is found in a famous story in the Masnavi of Maulana-e Rum (daftar 2). In it an event has been told about Hazrat Musa, that he saw a cowherd who was saying to God,

'Tell me where You are, so I may serve You.
I would sew and stitch up Your clothes,
I would wash Your clothes, I would kill Your lice,
I would bring milk to serve You, oh Great One.'

In short, that ignorant cowhers was saying many things of this kind that were absolutely contrary to the glory of God. Hazrat became very vexed with him, and scolded him harshly: 'You've said things that have destroyed your [proper] faith'. The cowherd, overcome by shame and sorrow, set out for the desert. But Hazrat Musa was reproved by God Most High: 'Who are you to steal away My servants from Me? I have made for every person a temperament, a nature. If something is good for someone, then it's bad for someone else.' God does not need anyone's knowledge or acquaintance:

'I did not give commandments for My benefit,
Rather, to be liberal to My servants.
The Hindustanis praise Me in terms of India,
The Sindis praise Me in terms of Sind.
I do not become pure through their glorification,
They become pure and pearl-scattering.
I do not look at the outer and the verbal,
I look at the inner and the real condition.'

It's clear that that cowherd was near to God, but he himself was uninformed about his nearness. Thus he was unable to show anyone else the road to nearness to God. Rather, even a great prophet like Hazrat Musa remained uninformed about his rank. Thus in Mir's verse too, one possibility of the meaning is, 'If I would obtain information about you, then how would I obtain it? For even the one who is a mystic-knower, does not know that he himself is a mystic-knower.'

In addition to the story told by Maulana Rum, another 'warrant' for this meaning of the verse comes from a saying of Shaikh 'Attar. Shaikh 'Attar commands in the tażkirah ul-auliyah ,

'There are many kinds of great Friends of God. Among them some are people of mystical knowledge; some are people of love; some are people of monotheism; some are praiseworthy through all the qualities; some are possessors of ordinary qualities; and some have emerged even without qualities.'

The meaning of this is that it is hardly strange of one of the 'people of love', of one of those Friends of God who would be without qualities, would be uninformed about his own mystic-knowledge. [Maulana-e Rum would agree, and in his mystic verses so would Mir.]

[See also {1746,8}.]

FWP:

SETS == SYMMETRY
MOTIFS
NAMES
TERMS == THEME; WARRANT

The second line is a devastatingly effective example of poetic use of the basic Urdu grammatical feature that I call 'symmetry'-- if one asserts that A=B, then equally and inevitably one asserts that B=A. In the present verse, the equation is between the 'uninformed' person and the 'aware/informed' person, so of course the equation goes both ways.

If the verse is talking about a person who is seemingly (or professedly) 'aware/informed' (2a), then he is the one who is actually 'uninformed'. Because even apart from hypocrisy or self-promotion, ordinary worldly 'knowledge' doesn't get you anywhere when seeking the transcendent or divine.

If the verse is talking about a person who is seemingly 'uninformed' (2b), then he is the one who is actually 'aware/informed'. This is the situation discussed at length by SRF; access to the transcendent/divine is full of paradoxes and mysteries. One hallmark of the true mystic-knower is that he has no pretensions to knowledge.

By no coincidence, both readings work perfectly to explain the despairing tone of the question in the first line.