Quick replace #N/A by 0 when vlookup

Which version of Excel? In Excel 2007 or later you can use IFERROR function like this

=IFERROR(VLOOKUP(A1,B2:E3,4,0),0)

You can also use IFNA if you only want to detect #N/A errors.

=IFNA(Formula,0)

This will display 0 instead of the #N/A error.