If you remember where your character was when you went offline it could help find a possible solution.
With the current undermesh and falling through the ground issues already reported to Funcom, it suggests that any players dying or logging off in certain areas or terrain types (cliffs, tunnels, caves, water, etc) may be dropping through the mesh during the logging back in process. This means that the character dies (again) and the loot also drops through the ground and is lost.
I say this because I have noticed I will sometimes log in and be dropping through the mesh. Because it has happened to me in the past, I an careful, where possible, to log off on normal ground. I did find once or twice that as I usually have largeish bases and I know that there are issues when I am logging back in whilst insde the base. I now try to be sitting on land a little way away from my base, not ‘looking’ in the direction of the base, whe I log out.