If energy can't be created from nothing, where does the energy come from to create black holes?

....but mass is energy

The first energies were created by something.
What you see in the giant bodies above you on the other hand are in a depleting cycle. So black holes actually do have energy that comes from mass.
They generate tremendous gravity while softly spinning around like an autistic hedgehog that curled into itself too fast on a slippery floor.

Gravity isnt energy

That sounds communists

They fuse all their lighter elements into heavier ones, so they can no longer produce energy. When a star is alive, the fusion in its core generates radiation pressure, which acts against gravity, making the star bigger. When the radiation pressure is gone because all the fuel has been used, the star collapses on itself, and if it's heavy enough, it becomes a black hole.

I think you could dump a ton of hydrogen on it, if it wasn't a black hole, just a white dwarf or something. You can't resurrect it without giving it new fuel, because you would have to turn all of its atoms back into hydrogen and you would probably have to trigger fusion after that somehow, if you wanted to do that.

What is the mechanism for mass?

are blackholes even real

Hawking radiation is a meme.