Empty plot - Is it a simple fix?

Questions
,
1

Hi everyone,
When I ask Mathematica to Plot or Animate I see the axis but no line?
Is this a simple fix?

2

When that happens I find a very useful trick is to temporarily replace Plot with Table, like this:

Plot[x^2,{x,1,3}]

turns into

Table[x^2,{x,1,3}]

and then look at the contents of that table.

At least for me that always points out what I need to know.

3

Any details?