Picture of weed in mobile phone

4 months ago

I have a girlfriend she is 23 and i am 19.
We meets on morning on public place and we have taken some normal pics together in my phone.
One day at night we just went outside on car ( me and my girlfriend ,her cousin and her boyfriend ) ( her cousin and her boyfriend were minor) and the public caught us and they informed the police and the police took mine and her cousins boyfriend phone away and they said to us come back on morning and said to leave the girls at their home and we did that.
On the next day i went to the police station with my cousin and they gave my phone back! They didn't informed or anything to our parents and it's over!
On another day,
We planned to go mangalore on day time,
And her brother caught her phone ( I was given her a phone cause she don't have a phone). And her brother texted to me as her and he kidnapped me and hits me with 3 of his friends and he taken my phone. There was a weed stick picture in my phone taken from the collage senior's while they rag us on their pg room!, and her normal picture holding her shoulder like that and there was condoms in my bag! ( my friend ordered from play store reward for fun and there was no option to cancel the order and the product arrived 2 days earlier so i just kept that in my bag. And her brother saw that too. He recorded my video showing the condom and face and a video of showing the weed picture in my hand and my face. And he informed my parents all and they came there and he leaved me but he tooks my phone and said he will give that back when my father comes! And now my father arrived and he didn't gave the phone back he is saying some excuses like the phone contains her picture, we said to reset the device and give back but he don't want to give it back to us. Then he started to say I have done with her need to check the dna test and we agreed and then he kept being silent and he said the caught me at her house doing with her at night bla bla bla fake newses!!
The matter is he is not giving the phone back!! What's the law to get my mobile phone back from his?
I am only worried about the weed picture in my phone! So please say the law and the procedures that will i get my phone back and will i go to the jail for having the picture?