Microsoft Corp. plans to bring its Windows Phone software to 23 new countries and put the operating system on less expensive smartphones, part of an effort to win back market share lost to Google Inc. and Apple Inc.

Microsoft will kick off the expansion by opening mobile- application stores in China, Thailand, Venezuela and the 20 other nations by the end of the month, with phones arriving around the same time, said Terry Myerson, who oversees the company’s Windows Phone business. That will bring the total number of markets Microsoft serves to 63, letting it target 60 percent more buyers, he said.