wmd965 ultima - hotpoint?

washin machine stopped mid-cycle displayin error F01 - no water, check supply...
Pulled out machine & all still att. can c no reason why water supply s/b disrupted.
Do we need to re-boot the system ?
If so, which buttons to re-boot ?
Or is this a problem we need an engineer to resolve ?
Thanxs for your help.... :)