Landlords must follow specific state rules and procedures when evicting a tenant. A landlord who takes the law into his or her own hands—for example by changing the locks on your apartment door and removing your belongings—is violating the law. Tenants who are subject to this type of “self-help eviction” may sue their landlord in small claims court for money damages such as the cost of finding a temporary place to live. (See the Nolo article How to Sue Your Landlord for advice on this subject.) And in some states, courts may award punitive damages (extra penalties, such as several months’ rent) for especially egregious landlord behavior. See Nolo's state rules on illegal eviction procedures for details on your state rules, including the damages that may be available to tenants.
Even if your landlord threw away your property, but did not change your locks, you may have cause to sue your landlord. Landlords in most states must comply with specific rules as to how they handle any property that appears to be abandoned by the tenant. For details, see the Nolo article State Rules on Handling Abandoned Property.