Every landing is an aborted go-around... No landing clearance = go around. End of story.
Loss of comms is a different story altogether. My Jepps state the following in the Emergency Section:
- Squawk the appropriate emergency code and listen out on ATIS and/or voice modulated navaids.
- Transmit Intentions and normal position reports. Assume Transmitter is Operating and prefix calls with "TRANSMITTING BLIND"
- If practible, leave/avoid controlled/restricted airspace and areas of dense traffic. Establish visual navigation as soon as possible and land at the most suitable aerodrome.
In this case it comes down to the PIC on the day to make the call. If I were on short final and the radio suddenly fizzed without receiving a landing clearance, my initial reaction would be to go around, click the transponder over and try another approach. It all comes down to the situation...