Bicycle detail

My bike was taken from my room without my permission by the landlord and kept without a lock in the shed outside. I was in the UK for 2 weeks for holidays. When I came back, I didn't find my bike in the house, and asked my roommates, who said the landlord told them he is keeping the bike outside. All this time, I was available on WhatsApp, but they didn't even message me to ask/tell that they want to move my bike. When I checked my bike is missing from the shed. I discovered this on my return. My landlord isn't answering the phone.