Found this on another thread….
That is when I decided to try to shock my system to get it to turn on taste and smell again. As a cook, I know how important salt is to enhance the flavor of things – even magnify them.

So I tried something which was very simple. This totally restored both my taste and smell in one day.

Step 1: put 1 ½ teaspoons of salt in a cup or mug.
Step 2: Stir until dissolved.
Step 3: Swish a mouthful of the salt water around in your mouth 3 times and spit it out.
Step 4: Repeat until the glass is empty.

After about an hour I could both smell and taste again. It wasn’t fully restored but much better.
I repeated this 2 more times, once in the afternoon and once before going to bed.

The next morning I had regained 100% of my taste and about 80% of my smell. I’m going to continue this to see if I can get all my smell back.

You might need to do this more than 3 times – so do it as long as needed – it will also kill bacteria in your mouth – so not a waste of time anyway.