It's possible to create documents in official, obfuscated Nspire format (with TI's official software, or TI-Planet's online nCreator: https://tiplanet.org/forum/edittns.php ), but I'm definitely not sure that it's possible to search for text in such documents... and anyhow, TI's code is way too inefficient and limited for handling such a large amount of text.
Let's also mention mViewer ( http://tiplanet.org/forum/archives_voir.php?id=6601 ) for viewing images - but then, of course, you wouldn't be able to search for text.

Is there anyone who can help me? Let me know how much you want for it to develop it for me.

You need to realize that the Nspire series, unlike the TI-Z80 and TI-68k series, is a closed platform. TI's BASIC sucks (it cannot even read from the keyboard or draw pixels to the screen), and TI's proprietary Lua cannot access external files (among other instances of crippling), so your only hope would be native code... but TI strongly fights native code development (Ndless and client programs). They close the holes constantly, and people don't bother sufficiently with the platform for native code to be available in an uninterrupted manner. Those who want openness buy e.g. Raspberry Pis, 5x more powerful though 4x-6x cheaper than those grossly overpriced Nspires.

The nTxt Ndless program might help you... but there's no guarantee you'll be able to use it when the time comes (if the OS of your calculator is forcefully upgraded to a version which does not support Ndless, you're screwed).

I have version 3.2.3.1233

It's precisely one of the versions where Ndless does not work. For now, you can downgrade for OS 3.1.0.392, but nobody in their right mind doubts that TI will remove this possibility in OS 3.3.
What Nspire model do you have, BTW ? CX, Clickpad, Touchpad ? CAS or non-CAS ?

How can Ndless help me? What is it, and how can it do the trick?

Ndless is "the Nspire's jailbreak". It's a framework for making native code programs - which are the only way to fulfill your requirements (due to the sheer size of your data).
But TI is very strongly against users accessing the full power of their calculators - not only they don't attempt to help users doing just that, but they're actively trying to prevent them from doing so.

It's definitely possible for someone (not me) to write a program, or modify the existing one I mentioned (nTxt) if it does not fulfill your requirements... but as I wrote above:

The nTxt Ndless program might help you... but there's no guarantee you'll be able to use it when the time comes (if the OS of your calculator is forcefully upgraded to a version which does not support Ndless, you're screwed).

You just actually need to download the correct 3.1 OS for your calculator and transfer it to the Nspire.

That's the tutorial for Ndless, yes.

Download your 3.1 OS on this page depending on your Nspire model :
http://tiplanet.org/forum/archives_list.php?id=OS%20Nspire

Then click on the "telecharger" button.

Exams are coming up

Yes! The TI customer service told me that this device is able to also search, but once I ordered my calculator I cam across a lot of problems. First, the PC software + calculator app wasn't able to process so much text. And I'm not able to search within the text.

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I really need a program that works for me.

_{Edit(Eeems): merged double post}