Boxplot - how to rotate x-axis labels to 45°?

Thank you!

I used las=2 before. Results were vertical labels, which are too long and cut off in the output. Therefore I need to know or how to make 35-45° labels or how to show the whole text of the x-axis labels in the output.
And theme just won't work.
I can't run ggplot either:

disprt <- ggplot(aes(x=group, y=distances)) +
  geom_boxplot()

**Error:data must be a data frame, or other object coercible by fortify(), not an S3 object with class uneval
Did you accidentally pass aes() to the data argument?```