Even in pristine condition (no folds, no discoloration), it is worth $20
$20.00
Twenty
I'm assuming you mean a Canadian half dollar, if so then not a whole lot, silver was removed in Canadian coinage before 1969 and as such it is pretty much just worth face value which is 50 cents Canadian.
It's worth two cents for the copper.
20 dollars
The 1969 Kennedy half dollar is only 40% silver with a value about $3.25
Twenty five cents
A US Kennedy half dollar dated 1969 is only 40% silver with a value of about $2.00.
A 1969 silver Kennedy half dollar is worth $5 inn perfect condition. The value of the silver is worth $2.87.
25 cents
About $2.00 for the silver in it (40%)
Despite its age, the crease unfortunately means that your bill is only worth face value.