Tuscany shower faucet single lever turned to hot, water stops coming out of shower head
The hot water inlet side of your valve may be clogged with rust or mineral deposits.  I have had that happen before.  In my case there was a galvanized steel pipe section screwed directly into a copper pipe section, which always causes rust in the pipe (galvanic corrosion).

Based on having the red and green adjustments, this sounds like a single-handled valve with a cartridge in the center.  You will need to remove the valve cartridge to clean out any deposits.

Is this a newly-installed valve in the shower, or is it an existing valve that just recently started having problems?