Contacting advisor after long hiatus I am enrolled in a master in CS, and finished all course work. Professors were happy with my work and I managed a 3.7 GPA -good for my university-
 without too much effort. 
When it came to the thesis I had a lot of trouble, every problem was exciting right until the point when I settled on it, then it became uninteresting and bland. 
I eventually started working on a particular problem and had some preliminary results, not very promising, but something.

Then lots of things started to happen, with the end result that during the past six months later I changed jobs, sold my house, moved to a foreign country, married, but made no progress and had no contact with my advisor. 

Now the question: I want to get back in touch and finish the degree as all-but-thesis is not a status I want to remain in. I would also like to change my advisor since my current one is not very engaged nor gives much time or attention to the advised students. Most of the students under my advisor finished six to 10 months after other students, despite no particular trend in the complexity of the thesis.

Is there any recommendations you can give as to how to word the first communication? I was planning on being simply honest and get to the point fast, but I have no clue if this is a good approach.

Thanks. If something is unclear please ask away, english is not my first language.
I've been in a similar situation, and these are the things I took into consideration:


is it feasible to work on your thesis from abroad? Labwork would make that a lot harder, whereas computer simulations can also be done on a beach in Hawai.
do you have enough progress to finish the thesis rather independently? If so, I would try to write everything up and get it over with. 
How easy is it to change advisors? I know it is possible at my institution, but not easy to get done due to the paperwork and the different boards involved. Plus, it often means a change in subject so you basically have to start all over again. Is it worth the effort?


My gut feeling tells me you best just put some elbow grease on, devote some time to your thesis and wrap it up. Take it from somebody who spent three years struggling to finish a thesis due to work: you want to get it over with so you can move on.

So what I would do, is:


write up a bit more, so you add some beef to your work.
roughly plan the rest of your work: when will the results be written out, when will the discussion be written out, still simulations to do? etc. 
send an e-mail to your advisor explaining briefly that you had little time to work on the thesis due to personal reasons the past six months, but you want to finish the work in a timely manner. In a next paragraph, explain briefly where you're at now. Make sure to include briefly what you've done since you last contacted him. In a third paragraph, briefly give your planning and ask him whether he can agree on the feasibility of the planning.


You have to keep in mind:


supervisors often have more students. So big chance your supervisor doesn't remember the details of your thesis any more. That's why the brief summary is important.
supervisors like to see results. So if you show them effort, they often get more engaged in the discussion. A little initiative can go a long way, and showing initiative in your first contact mail is likely to get his attention.
a supervisors mailbox can get well over hundred emails in a day. They have little time, so keep it short. "Briefly" is the most important word in my answer ;-)


It might be possible that your mail get snowed under in your supervisor's mailbox. So if he didn't answer after a week, a gentle reminder mail -including the original information so he doesn't have to dive into his mailbox to find it - can do wonders.

Good luck with it!