There are a few things you can try, smudge sticks (sage is best) are my favourite; you can use visualisation; I have heard of people using bells - the ringing of the bells creates a vibration which shifts the energy to a different level, although I have bells it doesn't 'do it' for me on it's own.
You could try looking at your furniture, what you have, how it's arranged, introduce a bit of Feng Shui? I am a huge fan of indoor plants....


I think a lot of it comes back to when you think about energy... it makes sense that we create so much of the energy around us. Think of it like a bad smell.. if we are exuding bad smell, the air around us stinks. If we, or our surroundings are (even inadvertently) exuding bad energy, then it will feel awful.

So what is it that you don't like & want to change? and what is it that you want to create?

Is moving an option? if it were me and it was really bad, and moving was an option I would be considering that.

ETA - a few other things - salt. My mother used salt once - you sprinkle it around the place, doors, windows, floors etc - and later (how long??) sweep it up & throw it away. Salt water is a great cleanser.
And light - you know the suncatcher things you can get that throw rainbows around, they are good.

That's all a bit all over the place sorry HTH