My 5 year old won’t won’t let me wash/brush her hair.

Hi all, 

my 5 year old daughter won’t let me wash her hair, it wasn’t a problem up until a year or so ago, I’ve tried all different ways, but now she’s refusing to get in the bath, I’ll run a bath hoping she’ll get in, sometimes she will but when I come in she jumps straight out. 

I can’t even hold a brush in my hand without her running off, I’ve tried holding her which she’ll just flop to the floor wiggles away screaming, I manage it looking half decent by throwing it up in a pony but it’s totally full of tats. I’ve even tried while she’s sleeping but feels I’m there,

could any body suggest anything that works to help unraveling the knots. any suggestions Welcome also thanks for taking the time to read