I'm sorry to hear that you are being troubled with nasty thoughts and images. It is a common symptom of anxiety, stress and/or low mood but there are various things that you could try. A list of options is detailed below:
1) ACCEPTANCE AND REFOCUS: Rather than trying to fight the thoughts and images it can help to just accept they are there, forgive yourself for thinking them, and then refocus on a task, a hobby, a project... anything that requires the brain to actively concentrate on and engage in something else.
2) MEDITATION OR MINDFULNESS: Some people find peace in meditation and mindfulness... by sitting still for a period of time each day with a candle, music or even listening to a guided meditation it can help to quieten the mind and enable us to simply become a witness to the thoughts.
3) COGNITIVE BEHAVIOURAL THERAPY: This is a method for intervening in continuous unwanted thoughts practised by the NHS and privately.Some GP's refer people to an online course which gives practical exercises to challenge the thought process. NLP and Life Coaching can also help with reframing thoughts.
4) CHANGE ENVIRONMENT: Going for a walk out in nature, sitting in a cafe reading a book, doing some gardening etc. By changing our outer environment we can help create positive change in our inner environment too.
5) AFFIRMATIONS AND GRATITUDES: Writing down a positive statement that is the opposite of your negative thought can be a helpful tip as can a list of gratitudes for all the good in your life. Some people choose to write down at least 5 gratitudes a day, before bed or on waking to start or end their day on an uplifting note.
6) REST AND SLEEP: Try get plenty of sleep and rest. Being over tired can be an invitation for unwanted thoughts, often remedied by giving yourself sufficient rest and recovery time.
7) EAT WHOLE FOODS AND KEEP HYDRATED: A drop in blood sugar or being dehydrated can also cause a drop in mood and energy, leading to negative thoughts.
8) DO SOMETHING YOU LOVE: By actively pursuing hobbies and interests that we love we can create feel good chemicals within the body which lead to a brighter state of mind.
9) HELP SOMEONE: Negative thoughts can be all consuming and by helping a friend or neighbour or offering support to someone in need, the focus moves out of self and into a state of giving.
10) CONSIDER HORMONES: The menopause and reduction in hormone production can dramatically effect mood. Do check our Menopause pages if you think your anxiety may be related to hormonal changes.
11) EXPRESS: If all else fails often the best way to release negative thoughts and images is just to write them down or tell a close friend. These thoughts and images tend to thrive in isolation so by admitting them, they often lose their power.
If you try these techniques and the thoughts and images continue to trouble you, it may help to speak to a healthcare practitioner, to avoid anxiety increasing or suppressing feelings which may need addressing.
I hope you find the method which works best for you.