Let's see who these actors are -
Kunwar Amarjeet Singh who is seen as Rey in Dil Dostii Dance on Channel V - Kunwar gained immense popularity for his character of Rey in the show. When there were reports that Kunwar is leaving the show, it came as a shock for the audience. He left the show as he participated in a dance reality show Dare 2 Dance on Life OK. Thus when he left the show entire caste and crew was left teary eyed. But now the actor is making a come back for a few episodes which will be definitely a treat for Kunwar's fans.
Ashish Chowdhry was seen as Raghav in Ek Mutthi Aasmaan on Zee TV - The actor left the show soon after his co star Rachana Parulkar took an exit from the show. After the exit of Ashish from the show, audiences lost interest in watching the show which resulted in low TRPs. Thus makers decided to pull the plug on the show and to give it a happy ending, Ashish was roped in for the last episode for the last episode.
Sunil Grover seen as Gutthi in Comedy Nights With Kapil on Colors - Sunil Grover who is well known for his feminine character Gutthi suddenly took an exit from the show which then led the viewers to loose interest in the show. Later the actor started a similar show on another channel but unfortunately that show was not able to grab the attention of the audience. Due to the low and dipping TRPs, the makers of Mad In India on Star Plus pull the plug on the show and he made a come back on Comedy Nights With Kapil. Audiences again accepted him back on the show open heartedly.
Vivian Dsena was seen as RK in Madhubala - Ek Ishq Ek Junoon on Colors - Vivian Dsena was loved by the audience a lot and also liked his arrogant RK's character in the show. But after Vivian took an exit from the show, TRPs of the show started dipping as the audience missed their RK in the show. Thus makers decided to bring Vivian back in the show to boost up the TRPs back and to some extent the show grabbed TRPs after Vivian's re-entry in the show.
Rashmi Desai was seen as Tapasya in Uttaran on Colors - Rashmi was loved by the audience for her role of Tapasya. When the show evovled further and took a leap, where Rashmi had to play the role of a mother of a grown up girl, she called it quits. Later she changed her decision as she found the script interesting, she made a comeback in the show.