Why Won't Single Cream Whip up?

Unfortunately if it is a recipe that requires the cream to be whipped then usually it is not possible as single cream does not have a high enough fat content to whip - it will not hold any air but will eventually turn into butter if you keep whipping it.

Why is my single cream not thickening?

You're not chilling your cream. Using room temperature cream is the cardinal sin of whipped creamery and the number one reason for whipped cream not thickening. If it reaches above 10°C, the fat inside the cream will not emulsify, meaning it can't hold the air particles which allow it to maintain fluffy peaks.

What do you do when whipped cream won't whip?

With the mixer running at low speed, slowly drizzle cold, unwhipped heavy cream into the mixing bowl. Keep adding cream until the broken whipped cream regains its fluffy texture.