Yadav, who is the Leader of Opposition in the Bihar Assembly, was not present on the first day of the Monsoon Session on Friday.
"Friends! For last few weeks, I was busy undergoing treatment for my long delayed ligament and ACL injury. However, I'm amused to see political opponents as well as a section of media cooking up spicy stories," he tweeted.
The former Deputy Chief Minister has been missing from public life since May 29, when he attended a Rashtriya Janata Dal (RJD) review meet to assess the reasons for the party's Lok Sabha election debacle.
In a strong message to his political rivals who have been taunting him over his absence from public life, he tweeted: "We are accountable to people who look for a socialist-secular and social justice alternative in us and wish to assure that we are very much here and the fight is on... Recent developments helped me study, scrutinise, analyse and appraise the things in a different way."
The younger son of RJD chief Lalu Prasad also expressed his concern over the deaths of more than 150 children due to Acute Encephalitis Syndrome (AES) in Muzaffarpur and areas surrounding it.
"Constantly following up the untimely loss of hundreds of poor kids due to AES. In this tragic moment, asked party workers and leaders to visit affected families without getting into photo-op and MPs to raise it in Parliament and that's why Prime Minister responded. My Dear Bihar! I am very much here," he tweeted.
In another tweet, the cricketer-turned-politician said: "Since its birth, the RJD has been at the centre of poor peoples' struggle and that position is not lost only because of an electoral defeat. Wish to assure the people of Bihar as well as our spirited cadre, we are going to fight with renewed commitment on everyday life issues of poor."
( With inputs from IANS )