Why is Wireshark showing no interfaces?

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Is there a way to add interfaces?

No, there is not.

And what you want is not a way to add interfaces; what you want is a way for Wireshark to find the interfaces if there are any, so you don't have to know what interfaces to add and don't have to to add them, they just show up.

Unfortunately, we don't know why Wireshark isn't showing the interfaces, and can't even do a good job of guessing why without knowing on what operating system you're running Wireshark, as the way capture devices work is very operating-system-dependent.

So, if you want the problem fixed, you'll have to tell us what operating system you're using, and what version of the operating system that is. Doing, as two people have already suggested, Help -> About Wireshark -> Copy to Clipboard from the menu, and pasting that information here, would get us most if not all of that information.