Landlord harassment for rent delays

    For a delayed rent payment can landlord :
1. File police case

No, as this is a private dispute.

2. Threaten to throw tenants out

Yes.

3. Change lock and refuse to give keys

4.  Use landlord keys to enter premises without prior notice

I dont think this is allowed, but he might do it nevertheless.

What are the  recourse for the tenant for these actions by landlord ?

Pay the rent, as you agreed to do when signing the rental contract.

Or move out.

Please read your tenant agreement and see what has written on it.

In general, you should adhere to pay the rent on time. if in a particular month you will pay late then inform your land lord in advance. But this should not be the regular case.

Owner doesnt have rights to come and open the unit which you have fully occupied. its trespassing someone’s occupied place and disturbing privacy.  But then read if anything it has written about it?

If owner came to know you are staying with other people without notifying the owner then he has rights to visit the unit without notifying you and may search rooms to check but not forcibly open.

But always good to have a good relationship with the owner so that it will be win win situation for both. Always try to follow the agreement.