it beats setting chrome to default in an attempt to fix it.
If the font was really changed then:
Open the hamburger menu.
Click on settings
Go to Advanced settings
Scroll to the fonts section
Click customize fonts.
If that doesn't help, then an extension might be the culprit. Open an incognito window to see if this is the case. If incognito mode isn't affected, you'll need to disable any suspicious extension until you find the culprit.
Hamburger menu --> More tools --> Extensions