well without more detail it's hard to tell, but it's a good idea to cleanse and protect your home every 6 months to a year depending. a very simple one would be to burn sage, wafting the smoke into every inch of the house, while saying a chant. afterwards, cat a protection spell on your house. a simple protection charm would do.
as mentioned above, sea salt can also help, sprinkle some around the outside of your house to keep negativity away. you can also place it on doorways and windowsills will do the same thing. i also read once a black mirror placed in the upper corner of the room can remove negativity. let it suck up all the negative energy in the room, once you feel it gone [or most if there's a lot] draw an equal armed cross [a + sign] on the mirror. this will seal the energy and keep it from returning. leave the mirror untouched for a week, then wash it with vinegar to get rid of all energy.
for the people, sage smoke can purify, but you might be better making a cleansing bath with sea salt and sage leaves [and/or other purifying herbs] to cleanse yourself of negativity. once you're done, shield [visualize a ball of white light around you] and wear a protection charm. the shielding should be done daily, while the cleansing and protection charm should be monthly. if you feel a negative presence still, repeat more often until the feeling is gone.