Laptop has been locked by a virus

Viruses & Threats
3

Greetings, 

We will help you in this.
Could you share us the snapshot of that message? 
You can post the screenshot here in your topic. Click on 'Answer' & then click on the 'Image' [mountain symbol] & follow the instructions.

1

Hello, my son's laptop has been locked by a virus. It's a grey screen which just says "YOUR COMPUTER IS NOW BUT YOU CAN REGAIN" 
There is no further information on the screen, nothing to click on and you can't get past this grey screen. As far as I know, AVG Antivirus is installed on the device.
can anybody help?
Kind regards 
Stephen

2

Greetings, 

We will help you in this.
Could you share us the snapshot of that message? 
You can post the screenshot here in your topic. Click on 'Answer' & then click on the 'Image' [mountain symbol] & follow the instructions.