Don't give up on them. I've had 35 year old Champagne that was fine, albeit stored around 55-60 degrees. Many whites will last that long too.
One important thing-- if you open a bottle and it isn't good, don't assume the rest are the same. There's a lot of variation and you may have found the only bad bottle in the bunch. There's certainly no harm in opening five bottles, discovering that the first four were bad, and enjoying the fifth.
And corks don't automatically dry up if bottles are upright-- after all, inside the bottle the humidity is 100%. So they may be fine.
But if by 'do these have any value' you mean that you want to sell them, it's going to be very difficult if they've been stored without proper temperature control.
So enjoy. At worst you spent a few minutes tasting wine you didn't like (or someone you give them to does).
Shaun Eli
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Brain Champagne: Clever Comedy for Smart Minds (sm)