Even More Renter Drama (or lack thereof)

I have been trying to get in contact with a tenant who was to pay me around the 15th. After several unsuccessful attempts, I asked the neighbor if he'd seen her and he replied, in short, that he thought she had moved out.
I went to the unit. The lights were on, so I called to the house several times with no answer. The tenants across the way were looking through their door and I inquired if they had seen my tenants. The volunteered that they'd helped my tenants move. I checked the gas meter and it was off, and the garage door was unlocked.
I opened the garage door. I looked at all the trash on the floor. At least they left the ladders they borrowed from me, and the paint they were going to use for the trim (that I had provided). I took some pictures, but they didn't upload like I wanted them to. The doors were all locked. I am not one of those landlords who carries keys to all the apartments, and I don't have them master keyed (though maybe I should reconsider that), so I loaded my ladders up and talked to the tenants from across the way.
They, M and J for now, said that my tenant mentioned that she owed money and was moving out. I don't know why she hasn't contacted me. I'm easy to get in touch with, by mail or phone. Someone's got to be able to lend you a phone.
Anyway, it's been quite the month for tenants leaving. One moved out due to moving into a senior park. Another left due to threat of eviction. This one just up and left--I only wish they'd just told me to come and pick up the keys. Another of my tenants is buying a house and I'm the agent and we're hoping to close this week, or early next.