How long will a cheap bottle of Korbel champagne keep in the fridge??

Hope it was stored on its side. If upright and the cork drys, I think you are in trouble but not positive.

 

It was on its' side.. But Really.. How long will it take a plastic cork to dry out??

 

You should never keep any wine in a regular fridge longer than 2 weeks.
The light and vibration will kill it pretty quickly,(knock all the nuance and fine taste out of it) If you have to drink it try putting a dash of bitters and a shot of brandy in it. It turns it into a cocktail.
If you want to replace it try some spanish sparkling wine
called Cava really good and readily available for around $10.00 US. :beer

 

You are WAY overthinking this thing.. It tasted just fine and was all consumed within a short period of time with return visits from many people when there were PLENTY of other options available. It was "pour what you want" and there was plenty to pour from..

I had a glass and it was as you would expect a low end sparkling wine to taste. I wasn't drinking for taste anyway..