Could there be dirt in the pipes? We had the same situation about a month ago, and were able to get a small compressor to blow air back through the pipes. It worked.
This happened to me too.
I had a tap that wasn't working properly.
I asked a plumber friend and he told me its very easy to fix.
I just went into a hardware store told the sales assistant what the problem was and he gave me a pack.
Went home turned the water off took the handle part of the tap off then unscrewed the tap spindle then screwed the new one in.
Had both taps done and dusted in 2 mins.