Travelling abroad without NOC

Sir, I am an employee of West Bengal Social Welfare Board, a statutory body run under 50% share of West Bengal State Government and 50% share of Central Social Welfare Board. Our authority is an honorary Chairman (appointed by W.B. Govt on 3 years term basis) and Secretary (who is a Welfare Officer of Central social welfare board, new delhi). I got married on 7th December'2014. At that time, the 3 years term of our at that time Chairman had ended a month before. So authority was only Head Assista t and Secretary. Further to note, that an IAS officer of State Govt. Was appointed on 14th December'2014 as Chairperson to run the office until the next chairman was appointed. But the officer had joined on 1st January'2015. In the mean time, I had applied for leave for my marriage and honeymoon to Bangkok and Pattaya from 8th December to 22nd December. From the time of formation of our board, our office did not use to give any leave sanction order, station leave permission nor any noc for leave sanction to our employees. Our Head Assistant or Leave dealing employee used to verbally announce us whether our leave was sanctioned or not. In my time also, I was verbally informed by the authority that my leave has been sanctioned which means I have been allowed to travel by the authority. So I had travelled at that time and made passport on our then chairman's permission. Now, on 2nd September'2019, our now chairman had issued a show cause letter to me asking me whether I had travelled abroad at that time or not. If yes, then on whose permission? Few days before, I have also come to know from her that some of my leave applications along with my file were missing from my personal file which remains in custody of our office and hence, remained unsanctioned by the authority which was not even informed to me by any means from the office. Now my file has been recovered from the dealing assistant of that time and is in custody of chairman but the leave applications are still missing. Whereas, I had applied for all the leaves everytime. Now, these question arises from my end.. 1. How can my file and records get missing which should be in safe custody of my office? 2. Why was I verbally told that my leave has been sanctioned whereas, it has not been sanctioned. And I was not informed about its non-sanction? 3. Why after a span of 4.5 years approx, this matter has been opened and I am given show-cause notice whereas, our at present chairman is our authority from June'2015 to till date? 4. What can the authority do with me? 5. Hence, what should I do now to save myself? Please help me save myself.