Lost stylesheet

Hello,

My site loads fine but my stylesheet is missing:

http://www.walsallccg.nhs.uk/

When I try and browse to my stylesheet:

http://www.walsallccg.nhs.uk/wp-content/themes/nhs/style.css

I get an error as if the file has been deleted.

In FTP its appears along with the other theme files, very weird, can anyone please help?

Thankyou