Hi i am a beginner in Arduino. I plan to interface my keyboard using Arduino and project it on my LCD (20x4). So when I pressed letter A on my Keyboard it will appear on the LCD. Is it possible? Any Suggestions/Tutorials? Thank you!
Hello and welcome 
Almost everything is possible but:
What kind of keyboard do you want to use? Your PC keyboard? Will the Arduino be connected to your PC? If yes, you can use the serial monitor, if not, you will have to use additional hardware, such as an USB host shield.
You must explain better what you are trying to do 
Yes i will use a USB PC Keyboard because i have not been able to buy a Keypad like this (Membrane 3x4 Matrix Keypad + extras [3x4] : ID 419 : $3.95 : Adafruit Industries, Unique & fun DIY electronics and kits) so i assume that i can use my PC Keyboard as an alternative to Keypad.
for the display i will use a Standard LCD 20x4 (Standard LCD 20x4 + extras [white on blue] : ID 198 : $17.95 : Adafruit Industries, Unique & fun DIY electronics and kits)
If the arduino is not connected to my PC, is there any alternative for USB Host Shield?
That is quite an assumption.
The keypad is very different from the keyboard.
The pad has a matrix of switches, the keyboard sends a datastream to convey what keys were pressed.
That's a world of difference.
An Uno is an USB slave and cannot be made to a host because of the nature of this setup (off chip USB interface).
But a Leonardo can be made to a host.
And if you want to stick to the Uno, you can use the USB host shield or.
The Mega ADK has an integrated USB host "shield".