outside stop valve

hi all I have installed this last summer and worked ok at the time. During the winter, it had not been used at all for at least 5 - 6 months. I tried to use it last week, but no water was coming out when opened the tap. What could be wrong, and where do I have to look to sort it? Thanks in...

I am trying to turn the mains water off to fix a leak in the house. Got a toby key(stopcock key) and turned the outside(under pavement) valve clockwise quarter of a turn as suggested by Scottish Water but the water still runs. Tried many times but the valve kept turning but not closing or...