If your plan failed in front of everyone, say it failed. Then show them plan B.

A public failure has already been seen, so pretending otherwise only adds the awkwardness of watching you pretend. Naming it clears the subject in one sentence and puts you back in charge of what happens next. What people remember afterward is rarely the collapse, it is what you did in the following five minutes. Most of them are relieved somebody said it plainly.

Use the short version: that did not work. Then move straight to what you are trying instead, even if it is rough and half formed. Having a second idea ready is the difference between a bad afternoon and a reputation for being steady.