Landlord/Tenant Return of security deposit?

I was given a 28 day notice to vacate. The 28th day actually fell on the 1st (which was a Friday). I advised the landlord that I will complete my move in the morning. When I came there, he changed the locks and had all of my stuff piled in one room. I took my belongings and left. Now, the landlord sent me a letter saying my deposit is being held for various reasons, mainly because I didn't clean up and didn't throw away stuff. Is this legal? He also charged me extra money for that Saturday, but I wasn't even allowed to go in the unit other than to grab my belongings. Can someone help me?