Fermentation Did Not Start

I'm looking for advice on what to do with my most recent batch of beer. I brewed an American Wheat on Friday night and pitched around 9pm. There was little to no noticeable activity in the fermentation bucket all weekend. I recognize this could be because of many factors, most often it's because of a seal that is not perfectly tight. Because of this I was patient and gave the beer over 72 hours and then decided to take a gravity reading.

It is clear that fermentation didn't start, I think we used an old/dead yeast.

The advice I am looking for is what to do next. I haven't found much helpful advice on the internet because most people haven't actually taken a reading with their hydrometers and their batches were actually fermenting despite the lack of bubbles in the airlock.

Please give me advice on how to proceed, I would like to salvage this batch if possible..

Thank you in advance.

Make a starter in the future, it will let you know if you have viable yeast. For now I would go get more yeast...don't worry about a starter as you don't want to give it anymore time than possible for other bugs to take hold...and repitch.

I made a starter, I made it late in the game (inside 24 hours) and therefore I didn't really get a chance to know if the yeast was viable. I know that was a mistake, I was just so anxious to brew again.

I have packets of US-05 and some packets of Champagne yeast sitting around. Also, I have an actively fermenting Belgian Wit right next to this defunct American Wheat.

I was contemplating pitching on the Belgian Wit yeast cake (I saw this recommended on other forums).

Thank you for your help..

I would say just pitch a packet of US-05 and let it begin. No need to mess around with an actively fermenting beer.

If you really want to use the yeast cake but it isn't ready you could get it started with the US-05 then rack it all onto the yeast cake in a few days. There's nothing wrong with mixed yeast strain fermentation, especially if you're looking for characteristics from both.

(This doesn't work for all yeasts. Most ale yeasts will get along together just fine, but wine yeasts, for example, will kill off almost any beer yeast and take over.)

Before you repitch, can you clarify whether there was any signs of activity in your starter (I understand it was still young when you pitched), what temp you pitched at and what the ambient temp is where your fermenter is?