Every once in a while, Visual Studio decides to mess up my colors.
This is what happens:
It should look like this:
I'm not sure what is causing this, but I hope someone else has experienced this before and was able to fix it.
Check this question at StackOverflow:
Basically the person asking the questing figures out himself that there is a plug-in overriding the colour settings. My tip would be to check any plug-ins you have installed and see if they have any font or colour settings
Also found this link although I don't know if it's really related.
It looks like you might be running ReSharper and have "color identifiers" enabled. They are optimized for a white background, I've had the same problem.
To fix go to ReSharper Options: Code Inspection/Settings and disable Color identifiers.
I don't know the reason they switch on and off, but it's probably because other users in your team have them enabled in their ReSharper "settings layer" which you can manage under ReSharper/Manage Options.
I've encountered this before. I've noticed that this usually occurs after I update an addon or a component.
While this isn't a permanent fix, I suggest that you make a backup of your fonts & colors settings.
The next time all your colors get messed up, simply import that settings file and your fonts & colors should be fine.
From the screenshots, it looks like the same color scheme with a few changes. Have you changed any of the colors yourself, or even just briefly experimented with themes? Did you for example, make a copy of a theme, change a few colors, then cancel?
A screenshot of your Theme menu can help narrow down the problem.
Next time the theme changes, make sure that the correct theme is still selected in the Theme menu. What may be happening is that now and then, you press some key combination or chord that triggers the theme to change (e.g., accidentally opening the Theme menu and pressing a key which corresponds to the other theme), or via a hotkey that specifically changes the theme (you can check this in the keyboard section of the Options dialog).