Need help on substitution worksheet

Hi and welcome.

Put this in AQ3 and drag across

=INDEX($C$3:$AO$41,MATCH(AQ2,$A$3:$A$41,0),MATCH(AQ1,$C$1:$AO$1,0))

Awesome Crooza! Works great. One more question. What would the code be to decipher? In AP4, I put "DC" then from AQ4 is where the deciphered text would go. The decipher instructions are at the bottom of the worksheet. To decipher, it would be the key text character from the left column and go across that row until the Cipher text (CT) character is found. The straight up to the top row to find the Plaintext (PT).

Put this in AQ4 and drag across

=INDEX($C$1:$AO$1,MATCH(AR3,OFFSET($C$1:$AO$1,MATCH(AR2,$A$3:$A41,0)+1,0),0))

Thank you again for the response and help. I had to modify it a bit. It seemed that it was one position over. Upon further investigation, the AR4 should have been AQ4. No biggie. I hope to one day be as knowledgeable as you. I only have one more question, which isn't a big issue, but I would like to know if I can modify this code to display nothing if the cell isn't being used. Currently, it displays "N" when not in use (Cipher), and "0" (decipher). Thanks again. You've been more help than I imagined.

Try this

=IF(AQ3="","",INDEX($C$1:$AO$1,MATCH(AQ3,OFFSET($C$1:$AO$1,MATCH(AQ2,$A$3:$A41,0)+1,0),0)))