Thanks for posting your query.
The tasteless feeling is due to the prolonged use or contact of toothpaste material on your tongue resulting in numbness
I would suggest you to rinse your mouth thoroughly using warm saline.
mouthrinse to gargle.
Floss your tongue using tongue scrapers.
Usually such numbness lasts for 24 hours only.
Please be careful while brushing your teeth,and only a pea-sized amount of toothpaste is usually used for brushing your teeth.
Drink plenty of water and fluids.
If symptoms persists,please do visit your dentist
and get a thorough evaluation done.
Also,intake of spicy,salty food has to be limited.