Filing law suit for not giving 30 days prior notice and fortifying the deposit money

We have rented a flat the flat owner dad was managing everything in the mont of July he has taken all our documents for security purpose and we also faves him then he told us that an agreement has to me make of 11 month but at that time we told him to make 9 month agreement due to academic session he okay from August we starting leaving flat and paid a security deposit of rent amount which he told he will cut it in last month of agrement and u dont have to pay for last month we said okay after the owner was dealing with us for any problem in flat facilities in mid of these nine month the owner asked until we u are going to vacate the flat we told him in first week of May then this corona pandemic started and we left flat and the our belongings were there only due to which we locked the flat and took the keys with us in this month we failed to provide rent on time and given 15 days late then asked us and we told him that we wil vacate in may at that time he told us to give on month notice before vacating the flat then ask rent again. We asked him to deposit as earlier his father told the last month will be adjusted with it and u dont want to pay rent but he told us u will get u r deposit at time of inspection of flat then we provide full April month rent with delay of 20 days now on 3rd May he ask us for rent we told him due to pandemic we can't provide u rent we are leaving flat then he says u have to pay rent for this as 30 days prior notice is to be giving before vacating the flat and his didn't make agreement also of 9 months and our belongings are still in flat and he asking for full may month rent then only he will think about giving belongingness and else deposit will be fortified and will give our once the may rent is given he giving threat of legal action against us and to apply law suites on us for not giving 30 days notice. And filling fraudulent case against us what to do pls guide and help us??