Replace the following values by VBA

Hello everyone,
I would like to replace the following values by VBA:
(a) by (1)
(b) by (2)
(c) by (3)
etc.

I would like to enter the maximum number of replacements using the input box window.
FOR EXAMPLE
23
Then the last replacement would be
(W) by (23)

The whole vba should only apply to the currently active sheet.

Thanks for your help

My sincere apologies.
The letters to be replaced by numbers are behind a word or behind numbers or in the middle:

FOR EXAMPLE:
ProTech - digital future (a)

or
ProTech - (a) digital future

or
(a) ProTech - digital future

or

1234 (a) zun769o

I am so sorry that I forgot to mention this.

Thanks a great lot.
It workes perfectly.

I apologize again for the extra work