Q.bougainvillia
i was given 2 bougainvillia plants last autumn, they are in large pots and were utside all winter, in the mountains in central portugal, it was a mild winter, but there was some frost. they now have no leaves or new growth, will they recover and grow more leaves

Bougainvillea are cold sensitive. Temperatures of 32 - 40 degrees F will likely kill the plant.
If they are in containers they are more vulnerable to cold damage.
https://www.gardeningknowhow.com/ornamental/vines/bougainvillea/bougainvillea-in-containers.htm