Luckily I have a backup plan of pre-made pearls just in case this very thing happened~ ˝/\___/\˝ (❀;≧∇≦;)
You either left it in the fridge for too long or there wasn't enough liquid. If its rock solid, throw it in the microwave while submerged in milk tea, it should soften it.
˝/\___/\˝
(❀;≧∇≦;)