Ooh yes, had months of speech therapy when I was an NQT. The main advice from therapist was to be very deliberate in breathing before speaking to the class, supporting the voice with extra breath.
She also suggested singing with a nasal voice in the car on the way to work (eg Tammy Wynette songs, sung through the nose like bad karaoke) to develop 'head voice'.
Drink your drinks cooler than boiling eg put a bit of cold water in tea. If cold drinks, don't have them too cold. Tepid water was the disappointing suggestion for the best drink.
Swallow instead of coughing to clear your throat.
Force your throat to relax when it is all tenses up by breathing out hard, trying to breathe onto your hand about six inches from your mouth. Once you get a good constant breath pressure that you can feel on your hand, try to reproduce this but without making any breathy sounds. If you can concentrate and do this, it opens your throat out and counteracts the stress on your vocal chords (or whatever).
Once your throat is relaxed, try to make a very quiet clicking noise by clicking your vocal chords together. Think it is called an 'unvoiced glottal click'. You can probably find YouTube videos these days. This apparently helps 'reset' your vocal chords and retake control of your voice.
All this advice is from 18 years ago so speech therapy may have moved on, but I used it from then on and very rarely lost my voice, or was able to get it back by doing the exercises if it started to go, so I found it helpful.
Good luck. Losing your voice can be horrible and isolating.