@er_prashant_93 If you carried out the steps correctly and the only issue now is your computer and IDE recognizing your board and allowing you to upload a sketch, then try the steps below:
Install the board's core via the Arduino IDE:
· Tools > Board > Boards Manager
· Search for "Arduino AVR Boards"
· From the drop-down menu select latest version
· Click "Install/update"
· Wait for installation to finish
· Click "Close" and restart your IDE.
. Plug your board back to the computer and select the board and port via tools.
See https://www.arduino.cc/en/Guide/Cores
For clone boards, see Using Arduino IDE with unofficial Arduino clones bearing CH340 chip | by Andrey Semenyuk | Dev Genius
Note: Use a data USB cable and do not use a USB hub or USB 3.0 port.