Last month's rent

Probably not. Did you get all your possessions out or were you forced to leave them there after the other tenant moved in? If you had to leave them, I'd contact the police so you could get your stuff out. If you got your belongings out or if the police won't do anything, contact an attorney for what rights you have. Good luck.

it depends on your lease agreement. He shoudl have given you a credit for those 4 days but it depends on the agreement you made when you first moved in.

It is probably illegal in your state. Check Tenant's Rights laws for your state. If you had a signed lease agreement and you paid for the full month, you should have sole access until your last day of your paid month. check it out.

yes

that's not legal but it will be hard for you to get your money back. you'd have to go to civil court. it might not even be worth it.

hard to answer...

I would check your states tenants rights online. I had a problem with my landlord and I surfed the net until I found them. Good Luck!

If you pay for the full month, you are guaranteed the full month, unless you agree to terms otherwise. Technically, you should get a rebate (albeit, a small one) for those 4 days that you were not the sole tenant of the apartment. I'd contact the local rental tribunal for further information.

You can call the cops anyways because the appartment is still yours for 4 more days even if it's empty.

Probably not, but I'm not sure what you'd gain by pursuing it. You could probably make a claim in Small Claims Court.