How can I fix my V-tech Mirage C110 cordless phone?

The phone keeps flashing "base 1" "Int" I have only ever had one phone so no inteercom.

The phone does not ring only the base. When you lift the phone to answer the base continues ringing. If you try to get a line on the handset you just get an engaged sound. The handset does not seem to respond to the base. Can I reconnnect handset to base? There are no lights on the base. If I press the 'search' button on base the handset does not respond.

I do not know whether the pin no. has been changed from 0000. Is it possible to reset back to factory setting OR if I unplug base and remove batteries from handset allowing everything to go flat, will that clear the phone and enable me to start again.

All other functions eg. change ringtone, keylock, etc. seem to work okay and the battery shows fully charged. I am sure it is something quite simple that needs adjusting which I am not doing.

Please help