Alekh was 10 when his daadaji died and his mental breakdown happened as before they used to keep mentioning that Alekh behaves like a 10 year old boy. I remember Vasu saying once 'Alekh bada ho gaya lekin abhi bhi woh ek das saal ke bache ki tarah hain', and during his treatment also I remember hearing this at various places. So Alekh was 10, that means Ranvir should be maximum 8, as it is really difficult to have 2 kids at a gap of 1 year (though not impossible) considering the time taken for conceiving and delivery. So practically minimum 1 and half years gap would be apt. So Ranvir should be 23 and a half maximum.
Another thing to think about is, Sadhna was a graduate when she got married, so that means at that time she was 20-21 years. So now since its been atleast a year since Sadhna married Alekh, she should be maximum 21, which means Ragini should be around 22. Hmm, everyone are soo young and they are tangled in complicated relationship probs 😕!