I am so sorry to learn this happened to you!
It only costs around $50 to have the cylinder on the door changed by a professional locksmith and takes all of two seconds. You can also visit your local hardware store for security locks. My windows did not have safety locks when they were open in the city, so I purchased some. Who cares about the landlord. Tell them you were locked out and called someone if you don't want to tell the truth. To me it would be worth the sanity. Your safety is what is most important.
I know how it is to have important items taken from you. Right now I really feel for you and send you a big hug.
A friend of mine used who went through a lot used to remind me that material things can be replaced (I know, easier said than done and I am very sentimental), but people and living creatures cannot. Try to be good to yourself and take good care during this time.
Hang in there.... This is a very bad thing that happened and it would be good if you could make an appointment to talk about this with your therapist.
Any idea who this could be? Did anyone know you were out last night? Also, you may want to consider renter's insurance. One of my relative is a drug addict and it freaked me out that they had access to my things. A safe deposit box and a lock box are also good ideas for the future.
It is really upsetting what happened, it's no wonder you are upset... anyone would be! This is a very bad person who did this, and ultimately it is them that are responsible for the misery they caused. The upset that you feel right now is not just your PTSD... it's very invasive and abusive, what happened to you! I've had things stolen from me that meant a lot by people close to me (at least then they were close to me). The entire experience can set off multiple triggers and it is probably going to take a few days and some therapy to get your thoughts to settle.
Sending positive energy and hoping and praying you get through this and all the items are retrieved by you.
Looking forward to hearing updates, please remember to keep reaching out for support.
-LL