Looking up the character number for a given character in Excel can be a frustrating exercise. Here's how I solved it.
In each cell from A1:A255 fill down the following formula:
=CHAR(ROW())
- The ROW() function will return a number representing the number of the current row.
- The CHAR() function returns the character corresponding to the number passed to the function.
So by filling the formula down, the ROW() function automatically passes the numbers 1 through 255 to the CHAR() function.
I went ahead and did the hard work for you. Just download the sample workbook and you can look up characters whenever you want.
Screenshot:

Cells B1:B255 contain the =CHAR(ROW()) formula. Cell C1 has a Data Validation list of 1-255 applied to it; use the dropdown to select the appropriate number.
Cell C2 does the heavy lifting. It contains the formula =CHAR(C1) which prints the character selected in C1. The ActiveX textbox blindly displays the contents of C2. The cell is formatted with a white font so it appears invisible, making the textbox look like it "knows" the correct character to display.
Note that we could have also used this formula in C2: =VLOOKUP(C1,$A$1:$B$255,2,FALSE)
