It is possible to kill a mother if you don't feed it everything it needs to continue growing.
Most of the people I know that make a lot of vinegar keep a "fresh" hunk of their mother separated and feed it weekly.
That is the mother that they use small bits of to make their vinegars with.
When they take the mother out of the freshly made vinegar, they "rest" that mother for a few weeks to allow it to rejuvenate.
It sounds to me like you just went from vinegar to vinegar until the mother just wore out and gave up the ghost.
fear not, just go to the grocery store and buy a bottle of Bragg's, it has mother in it that you can use.