Are you visual?
The regulations - which vary slightly depending on where you are, although the principles are generally the same - say "If the failure occurs in VFR conditions, or if VFR conditions are encountered after the failure, each pilot shall continue the flight under VFR and land as soon as practicable."
There are various allowances for the important difference between 'land as soon as practicable' and 'as soon as possible', but it might be hard to explain how you conducted your entire trip without ever finding visual conditions. In particular, if you have not yet climbed into the clouds on the departure, and there is no compelling objection to just landing again, the expectation would be that you fly the visual circuit back to your runway of departure, and look out for light signals from the tower.