hello frnds
my plane got crashed last week, after that i checked  my all electronics evn motor with 10-20% throttle, every thing was ok. but today as i try to fly my plane motor stop rotating at 50 %, and its heating. my winding turned to black (little bit),

important

-battery is charged and ok
-winding resistance of motor is ok (1.3 ohm each)
-there is no vibration or jamming in motor
- its running well upto 50%                   

plz help me

Might be timing issues or issue with your esc. Try changing your esc and see if it happens again. There is a possibility your esc might have screwed up your motor. 

When the receiver has a brown-out the Electronic Speed Controller goes into "fail-safe" and stops the motor from running.  See if your servos still work when the motor cuts out.

Does your motor start smoothly or starts twitchy ?
what current is it drawing and what voltage ? 

i din't check the voltage or current but some important issues are remarkable as

- motor takes current more than normal bcos it start heahing
-before stopping motor an unusual sound(humming) produce from fuse lag just a couple of inch back from motor mounting
-as the motor stops it start a continues beep like peeeeeeeeeeeeeeeeeee til i pull back throttle to zero
-and last it happens at exact 50%
-motor works up to full trottle without props but produces humming sound at higher speed

i hv reprogrammed esc. is there any motor bearing or shaft issue

i would check the bearing and the shaft. The crash might have damaged them. The peee  sound might be from the bearings. I have had same issues with my 3800 kv motor at high rpm's.

Please specify the make model of motor and the esc.

Hobbymate HB2806 brushless motor, 1450 Kv
Hobbywing 30A speed controller

but i think problem has solved bcos after 20-30 testing my motor start smoking (lol)

RIP  .

Just be careful with your hobbwing esc, it might have burned your motor. I faced the same issue with compass warp motor, i was lucky enough to land it. 

it will also burn soon bcos motor windings got black