March 11 (Reuters) - The head of Texas’s power regulator told lawmakers on Thursday that any effort to retroactively reduce the power prices levied during a recent storm would lead to lawsuits that the state could lose. Commodity contracts that utilities and others use to hedge their prices have closed and ordering a change “will have consequences” for the power market, agriculture and other commodities that use such contracts, Public Utility Commission Chairman Arthur D’Andrea said in testimony before a state hearing. (Reporting by Gary McWilliams)