It is possible to over whip cream and when you over whip cream it becomes curdled and grainy.
However you can fix the over whipped cream by adding some more heavy cream and whipping it again until it's the right consistency.
Also you can make cream out of milk.
Cream and whip cream can be made when you have none and have some milk.
To make cream from milk all you need is some whole milk, butter and a little bit of elbow grease.
To make 1 cup of heavy cream from milk, mix 2/3 cup of whole milk with 1/3 cup melted butter.
Really, it is that simple.
Also as an alternative, if you don't have milk on hand, you can also use 1/6 cup butter and 7/8 cup half-and-half.
Cream is from milk so you can easily make homemade cream and homemade whipped cream from some milk you have and a few other simple ingredients.
It just takes a bit of effort to make the cream from milk but it can be done.
Homemade cream also tends to taste better than store bought cream does.