I have a recording of some of my friends singing a song at an event, but the mic got feedback for like 2 seconds and I can’t find a way to remove it… Help please?
You could post a little bit of good and then bad sound here.
https://forum.audacityteam.org/t/how-to-post-an-audio-sample/29851/1
You shouldn’t get too excited about a fix. Audacity doesn’t do well with cleaning up sound damage.
Koz
It is probably impossible to remove the feedback and end up with a perfect recording, but it is probably possible to make the feedback sound less bad.
I’d suggest that you post a couple of short audio samples as suggested by Koz.
I’d probably try a couple of different approaches to what sounds best (or whatever sounds least-bad 
).
The easiest (and maybe “best”) thing would be to use the [u]Envelope Tool[/u] to reduce the volume during the feedback. You’re not “fixing” the problem or hiding the fact that it happened, you’re just making it less annoying.
I’ve got a shelf-full of professionally-produced DVD concerts, and although I don’t specifically remember hearing this kind of thing I wouldn’t be surprised if there was some feedback in one or more of these recordings… It occasionally happens and it’s part of the “performance”. (Of course, these shows are edited and they usually record at least two shows and assemble the best takes for the DVD.)
Other approaches -
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Mute the sound completely. This will leave a 2-second gap. It will probably sound like a recording or production glitch (rather than a performance glitch) and is probably worse than hearing what actually happened.
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Chop-out the 2-seconds of feedback. Of course, this will mess-up the timing of the song, and again, it may sound like a recording/production glitch if you can’t make it sound perfect. If you do that, re-join the audio with a very-short crossfade rather than a hard-splice (which can leave a “click” or a “pop”). It’s sometimes better to chop-out a full measure (usually 4 beats) or a full-sentance or a full vocal phrase, or whatever sounds best (or least-bad).
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Replace the audio with similar audio from a different part of the song. This can work very well if the glitch/defect is in the chorus where the exact thing is repeated, and if you have the skills to pull it off. In fact, you could replace the entire chorus with the preceding or following chorus. Again, use crossfades instead of hard-splices. But, that takes lots of skill and a very-good ear (I’m not very good at it) and I’m sure it helps to have higher-end software where you can set-up a timing grid (showing beats & measures).