Your solution would not work for all cases. For example, shifting "JAZZ" up by 1 should result in "KBAA" but your program would output "KB[[". You also need to handle wraparound at the ends of the alphabet.
I'm curious, what sort of approaches do you take to your programming tasks at work? Is it more like e.g. writing SQL where you'd think more about relating sets of data rather than looping over individual items?
What exactly did you have trouble with? These really are simple problems, all you need are an understanding of loops, ASCII character codes, and basic arithmetic.
To be honest, I'm surprised a seasoned developer of 5+ years can't do these, or at least have a decent stab at them.