How to re-enable syntax highlighting in Vim?

Vim language highlighting has quit working only for one specific file.

I’ve been using Vim in WSL (Ubuntu) for several months now without problems. My PC is Windows 10 Professional. Strangely, Vim is no longer highlighting properly when I open a particular file.

Everything works fine with every other file, but if I open this one file, it does not display correctly. The syntax highlighting is gone. Line numbers, tabs, and end-of-file-tildes still follow the color scheme, but my actual code is simply colored white. Does anyone know how to fix this?

More details:

• The file type is *.v
• If I rename the file, it displays correctly.
• If multiple files are open at once (i.e. split view), every other file displays fine while this one file does not.
• The problem arose in the middle of a work session, and I changed nothing in the vimrc before the problem arose.
• After seeing the problem, I ran apt-get update and apt-get upgrade, followed by a restart.
• I tried changing the color scheme in my vimrc.

Nothing I tried worked. Any ideas or insight would be greatly appreciated. Thanks!