i can't get the nut (or whatever you call it) off the bleeder valve... 9mm is to small and 10mm is to big. I have tried every thing possible and now have rounded it off. What do I do? How will I bleed my lines? Thanks for all the help!

 

vice grips. no big deal.

 

Break out your trusty Vise-Grips. But, before you try to turn the fitting, give it a good rap with hammer....Of course you will need to replace the fitting with a new one or a suitable used one. (The fitting cap is probably 3/8", right in the middle of your 9mm and 10mm wrenches.....Lotta younger members don't remember the British system of wrench sizes: 1/16, 1/8, 3/16, 1/4, 5/16, 11/32, etc., all in fractions of an inch. The only odd-ball was that 19/32" weirdo.)
We used to have a handfull of wrenches to do all the jobs, but with the advent of the metric system we now need a million wrenches: Start with 4mm, 4.5mm, 5mm, 5.5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm.....19mm, 22mm and on and on.

 

Always use a box wrench on bleeder valves to keep from rounding them off. All newer Fords are from 9 - 13 mm metric.
Sounds like the bleeder was overtightened at one point or you have a corrosion weld.
PB blaster (let it sit) and vice grips set as tight as they will go (no dude, I mean really tight, so tight you have to use both hands to lock it) and a series of taps (not too hard) of a small hammer on the vice grips counter clockwise should do the trick. I had that problem once on a car and I know it is a true pain in the rear. I had used an open end wrench and rounded it off so after that fiasco, I bought a really nice set of metric box end wrenches and have not rounded anything off since.
Unless there is no other way, open end wrenches are nut killers.