Humming sound on playback

Hello

I am recording a voice track but when I play it back I get a humming in the background.
How can I omit or delete this humming? I did a recording yesterday with no issue at all and I have not changed the settings

I look forward to any assistance

Thank you
Regards

Simon
Windows 10 / Audacity 2.4.2

I did a recording yesterday with no issue at all and I have not changed the settings

If you’re using a laptop try it with the power supply/charger plugged in and on batteries only to see if that makes a difference.

What kind of microphone are you using? Are you using any additional hardware such as a USB audio interface or mixer?

Is it low frequency power line hum or a higher-pitch whine?