Question: why sonu in tmkoc changed?
Answer: Sonu had been missing from Taarak Mehta Ka Ooltah Chashmah for quite some time. In the show, she had left Gokuldham society to pursue higher studies. Nidhi Bhanushali who earlier portrayed the character had quit the show as she wanted to concentrate on her studies. ... Nidhi had replaced Jheel Mehta as Sonu in 2012.