You can try this:
Stop netxms server, and do a db check with this command:
nxdbmgr check -f
Then run netxms server again. There are 2 possibilities:
1- object is fully deleted
2- object is recreated (due to dependencies)
If 1.st alternative is occures, then you can create same object again.
if 2nd alternative is occures, then your object is back.
I hope there is not any other alternative
