Water in sink in bathroom trickling, no pressure. Limescale or washer?

Hi,

The hot water tap in my bathroom sink has completely stopped flowing and the cold is now going the same way.

I don't know if it is the washers that I need to change or whether it could be a build up of limescale in the pipes.

I have an ideal standard sink and the taps have an "s" type symbol on the top of each one. Sorry I cannot be more help with details of make and model..

How can I fix either problem please?