Prime Minister Ingvar Carlsson, head of Sweden's caretaker Cabinet, is ready to lead a new government to replace the one which resigned last week, the national news agency TT reported Thursday. Earlier Thursday, the Social Democratic leader informed Parliament Speaker Thage G. Peterson he was ready and able to present the government to the legislature for approval. He was expected to get active support from the small Communist Party and passive support for the comeback by the middle-of-the-road Center Party. His previous government resigned on Feb. 15 when the Communists joined other opposition parties to defeat a bill for a two-year wage and price freeze.