No Hot Water to my bathroom

[mraich]

I just changed a tap on the basin in the shower room. Before starting I turned off the mains water and the star valve which allows hot water - fed from the tank in the loft - to the bath, shower and basins. I noticed that the bath tap continued to drain while I was working on the basin tap. When I turned the star valve back on and the mains back all I get is mains water to the kitchen No water is coming through the hot water pipes. Any suggestions?
Many thanks.
mraich
P.S. I do not have radiators. Just a standalone hot water cylinder heated by gas.