Asked by user in Missouri.
I’m so sorry this happened to you.
You can certainly press criminal charges against the assailants and file a civil lawsuit for the damages caused by their actions under intentional tort law.
You may also be able to file a lawsuit against your landlord.
In Missouri, landlords have a duty to use “ordinary care” to protect against “foreseeable” crimes (See Aaron v. Havens, 758 S.W.2d 446, 447 (Mo. banc 1988).). In your case, the assault may have been foreseeable, particularly if you told your landlord about the first assault. Accordingly, your landlord might be liable if they failed to take any reasonable steps to make the apartment safer after the first assault (such as installing locks, security lights, or security cameras).
I would recommend meeting with an attorney in your area to discuss your legal options. You can find one using our free online directory.