external wall outside tap?

The external tap which feeds off a tee to internal kitchen sink cold supply via a stop tap has suddenly stopped working. Opens & shuts OK but no water. It is used every few days winter & summer and has never caused a problem for 14 years! Thinking it was u/s I fitted a new tap with no difference!
Could problem be with internal stop tap,(which seems to open & close OK). Water supply to internal kitchen tap is not affected.
Any guidance will be appreciated!
Thanks,Dave.