user16784: So I recently bought an Arduino along with an LCD module and two extra ATmega328P-PU ICs. Yesterday it was working just fine then I disconnected everything and reconnected it and this happened.
What could possibly go wrong?
Setup:

with microcontroller that came with the board:

user13432: 
So i recently bought an arduino along with lcd module and 2 extra atmega328p-pu ,yesterday it was working just fine then i disconnect everything and reconnect it and this happen, what could possibly go wrong ?

I hope you understand how difficult it is for anyone to help with this type of question. 
My quick answer is "follow the schematics and reconnect the wires correctly" and "double check all wires".
From the picture it looks like you need to adjust the LCD contrast and reduce the back-light. Please see typical schematics for this. 
Another rule-of-thumb is to use wire colors in a meaningful way. For instance, black for GND, red for VCC, yellow for data, blue for control, green for clock, etc. 
Cheers!

user2926: These 16x2 LCDs are fairly sensitive about their power requirements.
As a first step, I would check the VCC and GND wires are well connected, and closely connected on the breadboard near the LCD.
If your LCD display shows rubbish characters, check the 4 data lines are connected in the correct order.
Also it looks like the contrast is at minimum (or LED backlight at maximum).  It could just be the photo, but best check both of these.

16784: <p>So I recently bought an Arduino along with an LCD module and two extra ATmega328P-PU ICs. Yesterday it was working just fine then I disconnected everything and reconnected it and this happened.</p>
<p>What could possibly go wrong?</p>
<p>Setup:</p>
<p><a href="https://i.stack.imgur.com/mhd5m.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/mhd5m.jpg" alt="Photo of Arduino and 16 x 2 LCD display" /></a></p>
<p>with microcontroller that came with the board:</p>
 13432: <blockquote>
  <p>So i recently bought an arduino along with lcd module and 2 extra atmega328p-pu ,yesterday it was working just fine then i disconnect everything and reconnect it and this happen, what could possibly go wrong ?</p>
</blockquote>

<p>I hope you understand how difficult it is for anyone to help with this type of question. </p>

<p>My quick answer is "follow the schematics and reconnect the wires correctly" and "double check all wires".</p>

<p>From the picture it looks like you need to adjust the LCD contrast and reduce the back-light. Please see typical schematics for this. </p>

<p>Another rule-of-thumb is to use wire colors in a meaningful way. For instance, black for GND, red for VCC, yellow for data, blue for control, green for clock, etc. </p>

<p>Cheers!</p>
 2926: <p>These 16x2 LCDs are fairly sensitive about their power requirements.</p>

<p>As a first step, I would check the VCC and GND wires are well connected, and closely connected on the breadboard near the LCD.</p>

<p>If your LCD display shows rubbish characters, check the 4 data lines are connected in the correct order.</p>

<p>Also it looks like the contrast is at minimum (or LED backlight at maximum).  It could just be the photo, but best check both of these.</p>
