Vapers Tongue is when your cannot taste your e-liquid anymore. This can happen anytime but frequently happens when you are in the early stages of stopping smoking. It is the direct result of your taste buds redeveloping after how ever many years of being punished by the chemicals in smoking.
There are many different theories on a "cure" but often the vaper has to wait it out It can last an hour it could last weeks but in the main once your taste buds are back its short lived if it happens in the future. Try vaping some menthol or strong mint and stay hydrated would be our advice.