Mantra to Reverse Negativity
This was one of the first mantras I really fell in love with. I think I've chanted it more times than any other. It's called the magic mantra and is incredibly powerful. It can take any thought and reverse it.
Mantra: Ek Ong Kar Sat Gur Prasad
Complete Mantra: Ek Ong Kar Sat Gur Prasad, Sat Gur Prasad Ek Ong Kar
Translation: There is one Creator of all Creation. All is a blessing of the One Creator. This realization comes through Guru's Grace.
Info: Guru Nanak taught this mantra to his son, Baba Siri Chand. The mantra is said to contain the essence of the entire Siri Guru Granth Sahib and brings its energy to reside in the heart. It is believed to be the most powerful mantra. Yogi Bhajan referred to this mantra as the "Eyes of Indra", saying that the body is a temple through which one experiences the Infinite--all knowledge and bliss flow through you.
The mantra takes thought and reverses it to come out positive. A thought rides into your consciousness to be processed with "Ek Ong Kar Sat Gur Prasad," and comes out pure with, "Sat Gur Prasad Ek Ong Kar." Info - Spirit Voyage
This is the only mantra in Kundalini Yoga that I know of the comes with a warning. Yogi Bhajan says that utmost be chanted in complete reverence. The warning is that it will make you so magnetic that whatever you say or think after chanting it will come about, so you must take care to only be very, very positive.
It is also recommended that you always chant the Mangala Charan for protection before (Aad Guray Nameh 3 x).
You can find many beautiful versions of this mantra HERE.
My favorite version is with Jai Jagdeesh. You can do the mantra as part of the Indra Nittri Meditation with her below.