Unable to connect to computer with a cable

Hi everybody,
Since a few days, I cannot connect my phone to computer with a cable anymore. Usually, I swipe down from the top of the screen to access the notification shade, look for a notification that says “USB for charging” and change it to “USB for file transfer”. Now I have no notification, the phone is just charging.
The laptop and cable are the same. I cannot figure out what’s wrong.
Any ideas?

Perhaps your cable is faulty.

That’s highly unlikely, because I checked with two different cables. Anyway, I’ll be able to check tomorrow with more cables.