You should consult person injury attorneys in your area. The attorney should be experienced in premises liability. The attorney will tell you if you have a case. A landlord is not necessary liable just because a person fell in a common area of the complex.
If you need medical attention, you should immediately go to a doctor to evaluate your injuries. If the fall was caused by improper maintenance of the steps by your landlord, you may have a claim. In that case, you should consult a local attorney who handles personal injury matters.