Excel VLOOKUP is not working though I have followed exact syntax.
=VLOOKUP(C1,A1:B5,1,FALSE)
returns #N/A

Excel VLOOKUP is not working though I have followed exact syntax.
=VLOOKUP(C1,A1:B5,1,FALSE)
returns #N/A

Use this instead:
=INDEX(A1:A5,MATCH(C1,B1:B5,0))
returns 1 which I assume is what you want.
In fact, I would suggest (almost) always using this INDEX-MATCH combo rather than VLOOKUP. It's much more flexible.