Sorry to hear of the situation. The recovery of repressed memories is a highly controversial topic in Psychology. The American Psychological Association formed a working group (a group of people assigned to conduct a very specific task) to review existing research evidence relating to memories of childhood abuse and made several conclusions that are relevant here:
So, what we can take from this is that there is convincing evidence that memories can be repressed and then recovered after a long period of time BUT fake memories can form that seem real AND we don't really understand how to tell the difference between a real and fake memory.
My suggestion would be that if you do decide to try and recover lost memories (which is your right to do) keep in mind that there is serious doubt about whether you would be able to tell if the memories were real or not. The term False Memory Syndrome has been coined to describe situations in which a person's identity and relationships are affected by memories that aren't real. This is also a controversial concept.
There is no specific technique or therapy for recovering lost memories but the term Recovered Memory Therapy (RMT) refers to several controversial and/or unproven interviewing techniques, such as hypnosis and the use of sedative-hypnotics. Proponents of recovered memory claim that traumatic memories can be buried in the subconscious and affect current behavior, and that therapy can recover them in order to heal the individual.
As there is no specific technique or practice you could teach yourself your best strategy will be to begin to learn as much as you can about RMT and make a decision about whether it is potentially an area you could adapt for your own purposes. You can start by reading this summary here http://www.caic.org.au/fms-sra/rmt.htm
This is a very controversial area so my advise would be that you educate yourself fully on both sides of the argument before making any decisions. This is probably no the kind of answer you were hoping for but unfortunately there is no specific technique I can direct you towards. I have deliberately refrained from giving my own personal opinion on this matter and have tried to provide you with an unbiased summary of the current state of knowledge in this area. If you would like me to provide you with my own personal opinion I would be happy to do so.
I will stop here and wait for you to look at what I have written and get back to me with any questions you may have at this time.
My own personal opinion (and it is only my opinion) is that I wouldn't recommend trying to uncover repressed memories. I believe that information/memories have a habit of surfacing at the appropriate time and I think that you have the right attitude in neither wanting to force memories out or repress them.
I don't wish to preach to you about therapies so please excuse me if this is a question you don't wish to go into, but what kind of therapy have you tried? There is an excellent form of therapy for people who feel the urge to self-harm that can be used on a self-help basis. If you like I could direct you to some resources that you could look into on your own time.
I'm not sure what kind of therapy you've tried but the treatment generally regarded as the best approach to self-harming related difficulties is Dialectical Behavior Therapy (DBT). DBT combines standard cognitive-behavioral techniques for emotion regulation and reality-testing with concepts of distress tolerance, acceptance, and mindful awareness largely derived from Buddhist meditative practice.
You could start by taking a look at this excellent self-help program here (it's completely free). It deals with one of the key areas of DBT - distress tolerance - and I find it to be a really helpful program when working with my own patients. There are also a number of books that can assist people to learn Dialectical skills at home.If you are interested in doing some further reading I can recommend both thisbook here and this book here .I hope these are of some help. If you have further questions or would like me to clarify any part of my answer please let me know. If not.....I wish you the best of luck!