Problem pipework that dosent make sense.

[Gary80gas]

Stripping out hot and cold for new set of bathrooms and ensuite so identified hot and cold marked h and c on floor next to pipes. Shut it off and stripped all pipework out to floor level. Turned out a bit of spaghetti station pipework feeding from one side and disappearing other end of room into floor.
I ended with 2 pairs of open ended pipes either end of bathroom so fit an iso valve on each and turned water back on. Only one pipe the cold coming live, all other 3 dead no water. ??
The house has an annex working off same boiler and hot water not flowing, so I connected live cold to what I had marked as cold pipe (dead pipe at this point) back to boiler. Hot water restored in annex but still nothing in the 2 pipes either end of old bathroom. The hot to this bathroom and the annex all coming off same combi, if its running to one side of house it should be where I just capped it off?
So I have 2 of the pipes connected together looping the colds? The other two ends are dead but they were the hot pipes, remember the hot water is live in the annex off same boiler. Tracing pipework in this house is a nightmare
Dosent make sense to me, this should have been simple, can anyone spot my obvious mistake. This is giving me a headache. Help.

 

[Vee]

Have the valves properly reopened? Gates in particular can seem mysteriously shut when you think you opened them....

 

[Gary80gas]

Thanks I know what you mean with gate valves.
I shut water off from mains 1/4 turn valve outside property. No other valves opened or shut. No other valves on hot system as far as I know. All hot and cold fed from this supply. Restoring mains should have restored everything. Hot and cold fed bath, shower and basin and then disappeared back into void. As if bathroom on a ring circuit?

 

[Gary80gas]

Ok I can only assume that a hot combi fed pipe under mains 1- 1.5bar pressure had air locked. I tested the same dead pipe today and it was live... Still don't believe it. What else...