I have already discussed the installation of the Arduino Library in the Proteus.
To simulate the Arduino UNO and LCD circuit in the Proteus libraries for both Arduino and LCD must be installed in the Proteus. So Arduino code for LCD should be simulated first to avoid any error in the circuit and assembling and disassembling the circuit again and again. It is very important to check the code of Arduino before physical implementation as there are number of pins included in the Prototype. The LCD and Arduino interfacing is quite common in several projects.