RAR password recovery. What are my chances?

I want to open some RAR archive I created 10-15 years ago, and I do not remember the password. I know it is a modified version of one of my passwords (modified means letter changed to numbers or similar looking symbols etc.).

If the password is not a common dictionary word i.e. made of numbers and letters or even symbols, what are my chances are recovery? Is there anything that can be done?

Thank you everyone in advance.