Let me get this straight. You have not told us what the make and model of shower is and you expect us to suggest what is wrong with it.
Sorry but we aren't clairvoyants
The best one can offer is that the solenoid valve may have failed, the water may be shut off.
You may get some mileage by looking at www.showerdoc.com
Click through on the make, select the model and you may well find a swathe of frequently asked questions for that particular shower, towatds the bottom of the page.
They also offer free phone support.
ewterwq
January 2018
Automatic Answer
We may have found other answers which could help you.
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix baths and showers.