Sometimes, you can't find the average because it's undefined: it can happen with a Cauchy and a few other statistical distributions: the wikipedia page has a nice plot of how the first 2 moments don't converge https://en.wikipedia.org/wiki/Cauchy_distribution#History

When in doubt, don't use the mean: prefer more robust estimates, as even with degenerate statistical distributions, there are still some "good numbers to report" like the mode or the median.

And if you don't know statistics, just use a plot!