* Sept pvt sector jobs data better than expected * Yellen scheduled to speak later in the day * Ralph Lauren jumps after CEO says stepping down * Western Digital rises after Unisplendour investment * Indexes up: Dow 1.09 pct, S&P 1.24 pct, Nasdaq 1.49 pct (Updates to open) Sept 30 (Reuters) - Wall Street was sharply higher on Wednesday, helped by gains in energy and health care stocks, but the three major indexes were set for their worst quarter since 2011. The third quarter was rocked by highly volatile trading due to fears of slowing growth in China. Adding to investors' uncertainty, the U.S. Federal Reserve held off on raising rates at its September meeting. Investors will be keen to put the bruising quarter behind them and look ahead to the third-quarter earnings season, which begins next week. Data on Wednesday showed that the U.S. private sector added more jobs than expected in September, raising hopes of a strong reading in the government's payrolls report due Friday. The Fed has said it needs to see more improvement in the... More