Re leaving letter

Hi, I was working in a private-but authorized by the govt, sector (manufacturer of aeroplane parts) for about two years. Due to personal reasons (marriage), I was on leave for about one month, without any information to the company. Later when I returned, the MD was generous enough to accept me, requesting for a apology letter, which stated I will not repeat this, failing which the company can take any action against me. Later again I stopped working in my company without any notice. After a week, I received a notice telling, if you are not interested in continuing the job, return back the company properties. waiting for a week, I returned all the company documents through post. Later on their was no need for a job for me, hence didn't think of re leaving letter. Now again thinking to start up my career, I requested for re leaving letter through mail. In response, they asked for a resignation letter(hard copy), signed by me. I signed a resignation letter & posted them. But still I did not receive any re leaving letter from my previous company. Can you suggest me any method through which I can get my re leaving letter & my PF amount. (Any method out of court, as the company members are very good, & I dont like to bring them in front of law, & spoil my relation with them) Also when joining the company, I was not given the offer letter as well. So I will need to collect offer letter, re leaving letter, experience letter from that company. Anyone please suggest me some way for me.