  Multi-wavelength observations of prominence eruptions provide an opportunity
to uncover the physical mechanism of the triggering and the evolution process
of the eruption. In this paper, we investigated an erupting prominence on
October 14, 2012, recorded in H{\alpha}, EUV, and X-ray wavelengths. The
process of the eruption gives evidences on the existence of a helical magnetic
structure and showing the twist being converting to writhe. The estimated twist
is ~6{\pi} (3 turns), exceeding the threshold of the kink instability. The
rising plasma then reached a high speed, estimated at 228 km s-1, followed by a
sudden rapid acceleration at 2715 m s-2, and synchronous with a solar are.
Co-spatial cusp shaped structures were observed in both AIA 131{\AA} and
94{\AA} images, signifying the location of the magnetic reconnection. The
erupted flux rope finally undergone a deceleration with a maximum value of 391
m s-2, which is even larger than the free-fall acceleration on the Sun (273 m
s-2) , suggesting that the eruption finally failed, possibly due to an inward
magnetic tension force.
