Hot water to shower. New guy needs some help

[Gregory Kent York]

Hello
Recent complaint from spouse was the hot water almost immediately died while in shower...
Dutiful husband(me) checks hot water faucets in other parts of house, feels hot water EVERYWHERE except said shower. I am guessing the mixer valve may be the culprit but have ZERO idea what brand/manufacturer to ask for at plumbing supply house(Big box stores aren't any help)
These fixtures were replaced approx 12-15 years ago... How to proceed?

 

[Mike Rock]

Hello
Recent complaint from spouse was the hot water almost immediately died while in shower...
Dutiful husband(me) checks hot water faucets in other parts of house, feels hot water EVERYWHERE except said shower. I am guessing the mixer valve may be the culprit but have ZERO idea what brand/manufacturer to ask for at plumbing supply house(Big box stores aren't any help)
These fixtures were replaced approx 12-15 years ago... How to proceed?

Pictures would help.

 

[Sponsor]

 

[Dj2]

One handle faucet or two handle faucet.