I let someone move into my bldg in a 2 bedroom apt before she gave me the security n 1st months rent because she said she was A hurricane sandy victim n she was getting funds. She been in the apt 1.5 months n I haven't received a cent. She a avoids my calls everyday. Also the apt was for her her husband &3 kids. There are 5 other people living with her. Can I padlock the door? Is she trespassing if I haven't received any money?

Tenant law varies by state.
You could be in a gray area between tenant rights (meaning you have to evict) and charging her with fraud by calling the police. But it probably won't work, and the police will tell you it's a civil matter, and you have to give notice for non-payment of rent and then file for eviction at your courthouse.

No you can not pad lock the door, and you may try calling the police as joypultv suggested but I doubt they will do anything, but you can try.

You will have to give them a notice of eviction for non payment, then file in court to evict.

Next lesson learned, if you own rentals, this is a business, not a charity, if you want to do it as a charity, donate the cost of room to local church or non profit and let them find people to live there, at least you get tax deduction.

Every time, and I do mean every time I ever tried to be nice and help someone by breaking one of my own rental rules it has come back to hurt him.

Just think of the apartment trashed, holes in walls, carpet to be replaced, I had one even rip copper pipe from walls to sell before they left.

Give them a pay or quit notice and follow it with an eviction order. If you own a "bldg." you should know how to treat non paying tenants.

If you need a fourth person to say evict will you do it? You have it now, evict and brush up on what you should and should not do as a landlord, you got suckered bad. What state are you in? http://ago.mo.gov/publications/landlordtenant.htm