I accidentally delete system font and the context menu became no Arrows.
I don't remember what font I deleted, but end up re-installing it.

What will happen to context menu when you delete system font.

When I right click on desktop or any file or folder, the arrows are not shown.
In my case arrows became euro symbol €.
Maybe some user will became small rectangle □. (missing glyph squares/tofu)

System font is still located in your PC and you can easily re-install it!

I searched font name for the Arrows, it's "Segoe MDL2 Assets Regular".
You don't downloat it from internet. (it's risky!)
Because it is still located in your PC!

1. Open "C:\Windows\WinSxS".
2. Search segmdl2.ttf.
3. Right click and select install.
4. Reboot Windows.

That's all!
If you use explorer search in Step2, it takes some time. Wait patiently.
for 32bit windows, it might located under the foulder name start with "x86_microsoft-windows-font-truetype-segoeui_" or "amd64_microsoft-windows-font-truetype-segoeui_".