headlamps wont turn on on 1999 Buick Century

it can flash but high and low beam wont turn on

Asked by for the 1999 Buick Century
Usually the result of a poor (high resistance) connection at the headlight switch! Have the switch and the wire connector to the switch checked for signs of excessive heat, melted or deformed connector plug. If that is found the switch and connector needs to be replaced. Are the headlight bulbs original equipment type, number and candlepower, as far as you know? No high output or higher wattage bulbs installed?