I'm using Emacs 24 and elpy to run some Python 3 code. However, after I open a shell with C-U-C-C-C-Z and then run my code with C-U-C-C-C-C, I get the error in my command line: 

Cannot open load file: no such file or directory, pylint

This is odd, as I've made no recent changes to Emacs, but it always tends to be finicky about if it wants to run any code. The python shell works fine, so that shouldn't be the issue. Thanks.
Refer to @Ehvince's comment. Make sure that pylint, is in fact, installed using the command line.
Emacs fails to run Python code