# Plots dashed when I don't specify them to be dashed?

I was plotting a function (F here) with selected values, and just wanted the plot to be solid lines with the selected colors specified with PlotStyle:

Plot[{F[11, 2, x*1*^-6], F[18, 22, x*1*^-6], F[54, 77, x*1*^-6],
F[55, 78, x*1*^-6]}, {x, 0, 10*^3}, Frame -> True,
FrameLabel -> {"Recoil energy (eV)", "Nuclear form factor"},
ImageSize -> Medium,
PlotLegends -> { "23Na", "40Ar", "131 Xe", "133 Cs"},
PlotStyle -> {Red, Green, Blue, Orange},
LabelStyle -> {FontFamily -> "Courier", FontSize -> 14, Black}]


But when I evaluated this, I got the following output with dashed lines instead of solid lines:

This was not a problem until last night, and it occurred every time I plotted something that I wanted to be solid lines. I don't remember doing anything weird either last night.

The only thing that fixed it was copying everything in the notebook and re-evaluating it from scratch in a new one.

If anyone has any idea on what could've caused this to occur, I would be happy to hear about this.

• Does this still happen in a fresh kernel? Otherwise, it could just have been a glitch. – J. M.'s technical difficulties May 26 at 13:47
• It disappeared after starting in a fresh kernel. I think Mr.Wizard was correct with his response. I still haven't figured out what changed the PlotTheme setting to Monochrome though... – David Trimas May 27 at 3:03
• Perhaps you were trying things out earlier, and forgot about it. Usually, things you did at In[5] would still be remembered at In[1015]. – J. M.'s technical difficulties May 27 at 3:08

It appears something set $PlotTheme = "Monochrome"; $PlotTheme = "Monochrome";