Bad LCD? Bad microcontroller? Or what?
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!