G7979, thanks for the correction and clarification.
Thank you for your reply, I was subleting a room while I was living in the property. Once I have given the keys there were no people living in there. New tenants moved in next day. There were no property damage or anything like that.
The Op has not always been very clear, to my mind, as to when things happened.
On re-reading the posts several times, I now think I have misunderstood what the OP meant:
I was subletting a room while I was living in the property.
This should have been renting a room, not sub-letting.
next sentence:
Once I have given the keys there were no people living in there.
This, I understood as the OP gave the keys to the sub-tenant.
Following sentence: New tenants moved in next day.
My original understanding was that the sub-tenant took over when the OP vacated.
I now think the OP meant the following:
I was renting a room while living there, we I and my "lodger" (not sub-tenant) moved out at the end of the lease and the next day new tenants moved in.
In this case, the OP did not become a landlord under the definition for the PRTB, but was a live-in landlord renting a room in her home and not liable to PRTB registration. As the OP's landlord did not object to the OP having a lodger (licensee) although he knew about the new person in the property.
Therefore, to answer the OP's original question,
If she will take us to court or PRTB can she win a case? He wants us to pay him money to cover his loss of income and breach of contract.
IMHO, if the landlord made a claim against you for having another person in the property, he would not succeed and the OP should make a claim against the landlord for unjustifiably retaining the deposit. The OP should also claim for damage for the unjustifiable retention of the deposit.
To help people reading this thread, it should be clarified as to what sub-letting is.
A sub-let exists when a tenant renting a property, vacates the property and in turn rents the property to another tenant. Thus, the original tenant becomes a landlord in their own right and must comply with all rules and regulations relating to being a landlord. In a sub-let situation, there are two landlord involved: the landlord (probably the owner of the property) and the "Head tenant" (the original tenant) who is liable to the landlord for the rent. The head tenant may charge the sub-tenant more or less than the landlord (owner) charges the head tenant but the head tenant is responsible for the rent stated on his lease.