1.
If you throw something back at a person, you remind them of something bad they did in the past, in order to upset them.
I should never have told you that. I knew you’d throw it back at me.
PHRASAL VERB: V n P at n, also V P at n n
2.
If someone is thrown back on their own powers or resources, they have to use them, because there is nothing else they can use.
We are constantly thrown back on our own resources.
PHRASAL VERB: usu passive, be V-ed P on n